Zoom lens with five lens groups

ABSTRACT

A zoom lens is composed of a first lens group of a negative refractive power, a second lens group of a positive refractive power and a third lens group of a positive refractive power, in which, in the zooming operation from the wide angle end to the telephoto end, the distance between the first and second lens groups decreases, the distance between the second and third lens groups varies, the distance between the third and fourth lens groups increases, and the distance between the fourth and fifth lens groups decreases.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a zoom lens. In an aspect, it relatesto a wide-angle zoom lens adapted for use in a single lens reflexcamera, and more particularly to a zoom lens having a large apertureratio and suitable for automatic focusing. In another aspect, it relatesto a zooming method of the zoom lens, and more particularly to a zoomingmethod suitable for inner focusing.

2. Related Background Art

For zoom lenses, particularly those of wide angle for use in single-lensreflex cameras, there have been widely utilized a negative-positivetwo-group configuration and a negative-positive-negative-positive4-group configuration.

However, it has been difficult to achieve a large aperture ratio withthe negative-positive 2-group zoom lens. Also if thenegative-positive-negative-positive 4-group zoom lens is designed with alarge aperture ratio, the first focusing lens group becomes large, thusincreasing the burden on the motor in the case of auto focusing, so thata high focusing speed is difficult to achieve.

The focusing of the zoom lens is generally achieved by a method formoving the first lens group toward the object. Such a method is widelyutilized because of an advantage that the amount of movement of thefirst lens group for focusing to a given object distance does not dependon the focal length of the zoom lens.

Also, there have been proposed, for example in the Japanese PatentApplication Laid-open No. 57-5012, zoom lenses of an inner focus methodor a rear focus method in which a lens group, positioned closer to theimage plane than the first lens group, is moved for focusing.

The first group moving method, in which the relatively large and heavyfirst lens group is moved for focusing, is associated with a lowerfocusing speed when auto focusing, in comparison with the inner or rearfocusing method. It is also inadequate for a waterdrop-proof orwater-proof camera, as the outermost lens group has to be moved.

On the other hand, in the zoom lens of the rear focusing method proposedin Japanese Patent Application Laid-open No. 57-5012, the amount ofmovement of the focusing lens group, required for focusing to the objectat a given distance varies significantly depending on the focal lengthof the zoom lens, and the lens becomes defocused if a zooming operationis conducted after the lens is focused to the object at a shortdistance.

SUMMARY OF THE INVENTION

A first object of the present invention is to provide a zoom lens havinga large aperture ratio and a wide field angle, and still suitable forauto focusing.

The above-mentioned object can be attained, according to the presentinvention, by a zoom lens provided, in the order from the object side,at least with a first lens group of a negative refractive power, asecond lens group of a positive refractive power, a third lens group ofa positive refractive power and a fourth lens group of a negativerefractive power, wherein, in the zooming operation from the wide angleend to the telephoto end, the distance between the first and second lensgroups decreases, that between the second and third lens groups variesand that between the third and fourth lens groups increases.

In the above-mentioned configuration, the following condition ispreferably satisfied:

    0.3<f2/f3<3                                                (1-1)

wherein

f2: focal length of second lens group; and

f3: focal length of third lens group.

In the focusing operation from a long object distance to a short objectdistance, the second lens group is moved toward the image plane.

According to the present invention, in the conventionalnegative-positive-negative-positive 4-group zoom lens, the second lensgroup is divided into two positive groups, thereby reducing the positiverefractive powers both in the second and third lens groups and thusfacilitating the correction of aberrations and simplifying theconfiguration of these two lens groups. Also, the distance between thesecond and third lens groups is varied at the zooming, therebyfacilitating the correction of astigmatism and achieving satisfactorycorrection of the aberrations from the wide angle end to the telephotoend.

The condition (1-1) defines a range for obtaining such effects. Abovethe upper limit of the condition (1-1), the refractive power of thethird lens group becomes excessively large, so that the configurationthereof becomes difficult to simplify. On the other hand, below thelower limit of the condition (1-1), the refractive power of the secondlens group becomes excessively large, so that the configuration thereofbecomes difficult to simplify.

For focusing a zoom lens, there is generally employed the first groupmoving method of moving the first lens group toward the object, andfocusing by such a first group moving method is also possible in thezoom lens of the present invention, but the effective diameter of thefirst lens group becomes large if the field angle and the aperture ratioare made larger. In such a zoom lens, it is difficult to achievehigh-speed focusing as the movement of the first lens group in autofocusing gives a heavy burden on the focusing motor etc. In the presentinvention, therefore, the focusing from a long object distance to ashort object distance is achieved by a movement of the relatively smallsecond lens group toward the image plane, thereby achieving a high-speedfocusing operation when auto focusing. Besides, a configurationsatisfying the aforementioned condition (1-1) reduces the difference,between the wide angle end and the telephoto end, in the amount offocusing movement of the second lens group, and is therefore convenientin case zooming is conducted after focusing, or in case the manualzooming is utilized in combination.

It is furthermore possible to maintain the first lens group fixed at thezooming operation, by varying the distance between the second and thirdlens groups for correcting the position of the image plane at thezooming operation. Thus, in combination with the inner focusing method,it is possible to maintain the first lens group fixed in the zooming andfocusing operations, so that there can be realized a zoom lens resistantto the external shock and to the intrusion of waterdrops and dusts.

It is also possible, at the zooming operation, to integrally move thethird and fifth lens groups or to maintain the fourth lens group fixed,thereby simplifying the configuration of the zoom lens.

A second object of the present invention is to provide a zoom lens inwhich, even in the use of the inner focusing method, the amount ofmovement of the focusing lens group required for focusing to the objectof a given distance remains substantially constant regardless of thefocal length of the zoom lens.

The above-mentioned second object can be attained, according to thepresent invention, by a zoom lens provided, in the order from the objectside, with a first lens group of a negative refractive power, a secondlens group of a positive refractive power and a third lens group of apositive refractive power, wherein, at the zooming operation from thewide angle end to the telephoto end, the first lens group remains fixed,the second and third lens groups move toward the object side with avarying distance therebetween, and the imaging magnification of thesecond lens group does not become -1 in any focal length between thewide angle end to the telephoto end.

Also, there is provided a configuration provided, in the order from theobject side, with a first lens group of a negative refractive power, asecond lens group of a positive refractive power, and a third lens groupof a positive refractive power, wherein, in the zooming operation fromthe wide angle end to the telephoto end, the distance between the firstand second lens group and that between the second and third lens groupsvary, and the focusing from a long object distance to a short objectdistance is achieved by the movement of the second lens group toward theimage plane.

Also, there is provided a configuration provided, in the order from theobject side, with a first lens group of a negative refractive power, asecond lens group of a positive refractive power, a third lens group ofa positive refractive power, and a fourth lens group of a negativerefractive power, wherein, at the zooming from the wide angle end to thetelephoto end, the distance between the first and second lens groupsdecreases, that between the second and third lens groups increases andthat between the third and fourth lens groups increases.

Also, there is provided a configuration provided, in the order from theobject side, with a first lens group of a negative refractive power, asecond lens group of a positive refractive power, a third lens group ofa positive refractive power, and a fourth lens group of a negativerefractive power, wherein, at the zooming from the wide angle end to thetelephoto end, the first lens groups remains fixed, the distance betweenthe first and second lens groups decreases, that between the second andthird lens groups varies and that between the third and fourth lensgroups increases.

Also, there is provided a configuration provided, in the order from theobject side, with a first lens group of a negative refractive power, asecond lens group of a positive refractive power, a third lens group ofa positive refractive power, a fourth lens group of a negativerefractive power, and a fifth lens group of a positive refractive power,wherein, at the zooming from the wide angle end to the telephoto end,the distance between the first and second lens groups decreases, thatbetween the second and third lens groups varies, that between the thirdand fourth lens groups increases, and that between the fourth and fifthlens groups decreases.

Also, there is provided a configuration provided, in the order from theobject side, with a first lens group of a negative refractive power,with a second lens group of a positive refractive power, a third lensgroup of a positive refractive power, and a fourth lens group of apositive refractive power, wherein, at the zooming from the wide angleend to the telephoto end, the distance between the first and second lensgroups decreases, that between the second and third lens groups and thatbetween the third and fourth lens groups vary, and the focusing from along object distance to a short object distance is achieved by themovement of the second lens group toward the image plane.

The foregoing configurations preferably satisfy at least one of thefollowing conditions:

    |β2t|>2                             (2-1)

    |β2w|>2                             (2-2)

    β2t>2                                                 (2-3)

    β2w<-2                                                (2-4)

    0.5<f2/f3<2                                                (2-5)

    f2/(|f1|+e1t)>0.8(f1<0)                  (2-6)

    f2/(|f1|+e1w)<1.2                        (2-7)

wherein

β2t: imaging magnification of the second lens group at the telephotoend;

β2w: imaging magnification of the second lens group at the wide angleend;

f1: focal length of the first lens group;

f2: focal length of the second lens group;

f3: focal length of the third lens group;

e1w: distance from the image-side principal point of the first lensgroup to the object-side principal point of the second lens group at thewide angle end; and

e1t: distance from the image-side principal point of the first lensgroup to the object-side principal point of the second lens group at thetelephoto end.

Also, in the case of the zoom lens consisting of the negative first lensgroup, the positive second lens group and the positive third lens group,the following conditions are preferably satisfied:

    f3/e3w>0.8                                                 (2-8)

    f3/e3t<1.2                                                 (2-9)

wherein

e3w: distance from the image-side principal point of the third lensgroup to the image plane at the wide angle end;

e3t: distance from the image-side principal point of the third lensgroup to the image plane at the telephoto end.

The zoom lens attaining the second object of the present invention isprovided, in the order from the object side, with a negative first lensgroup, a positive second lens group and a positive third lens group,wherein the second lens group is given a large imaging magnification inthe entire zooming range from the wide angle end to the telephoto end.

In such configuration, in effecting the focusing by the movement of thesecond lens group toward the image plane, the amount Δ of focusingmovement of the second lens group can be approximated by:

    Δ≅{β.sup.2 /(β.sup.2 -1)}·{f1.sup.2 /(D0-f1)}                                                 (2-10)

wherein

β: imaging magnification of the second lens group;

f1: focal length of the first lens group; and

D0: distance from the object point to the object-side principal point ofthe first lens group.

The f1 in the right-hand term of the equation (2-10) is a constant, andD0 becomes a constant in a zoom lens of which length does not vary inthe zooming operation. β varies in the zooming, but, if given a largeabsolute value, {β² /(β² -1)} approaches 1 and varies little in thezooming. Also the focusing becomes impossible if the imagingmagnification β of the second lens group is -1.

Based on these facts, |β| has to be made large in order to decrease thevariation, in the zooming, of the amount of the focusing movement of thesecond lens group. It is also desirable that D0 does not vary, or thefirst lens group does not move, in the zooming operation.

The conditions (2-1) and (2-2) define the value of |β| at the wide angleend and at the telephoto end. Below the lower limits of the conditions(2-1) and (2-2), the variation, in the zooming operation, of the amountof focusing movement of the second lens group undesirably increases. Theabove-mentioned variation can be further decreased by adopting "3" asthe lower limit of the conditions (2-1) and (2-2).

By selecting substantially same values for |β| at the wide angle end andat the telephoto end, the amount of focusing movement of the second lensgroup can be made approximately same at the wide angle end and at thetelephoto end. For achieving efficient zooming, in such case, it isdesirable to select the imaging magnification β2w of the second lensgroup at the wide angle end as negative and the image magnification β2tat the telephoto end as positive, and preferably to satisfy theconditions (2-3) and (2-4).

It is also possible to fix the first lens group, by using the second orthird lens group as a compensator. The condition (2-5) defines theappropriate ratio of the focal lengths of the second and third lensgroups, in such case. Below the lower limit of the condition (2-5), therefractive power of the second lens group increases and the sphericalaberration becomes difficult to correct. On the other hand, above theupper limit of the condition (2-5), it becomes difficult to secure theback focus distance and to reduce the entire length of the zoom lens.

In the case of varying the distance of the second and third lens groupsat the zooming from the wide angle end to the telephoto end with thesecond or third lens group used as the compensator, it is effective, forreducing the entire lens length, to increase the distance of the secondand third lens groups in the vicinity of the wide angle end and decreasethis distance in the vicinity of the telephoto end.

The conditions (2-6) and (2-7) define the appropriate relationship inthe first and second lens groups when the focusing is made with thesecond lens group. Below the lower limit of the condition (2-6) or abovethe upper limit of the condition (2-7), the variation, in the zoomingoperation, of the amount of focusing movement of the second lens groupbecomes undesirably large.

The conditions (2-8) and (2-9) define an appropriate range of the focallength of the third lens group, in case the focusing is made by thesecond lens group in a zoom lens consisting of a negative first lensgroup, a positive second lens group and a positive third lens group.Below the lower limit of the condition (2-8) or above the upper limit ofthe condition (2-9), the variation, in the zooming operation, of theamount of focusing movement of the second lens group becomes undesirablylarge.

The zoom lens attaining the second object of the present invention isbasically composed of a negative first lens group, a positive secondlens group and a positive third lens group, but there may be added, atthe image side, a positive or negative fourth lens group for increasingthe aperture ratio or reducing the dimension, or a negative fourth lensgroup and a positive fifth lens group for increasing the zoom ratio orthe aperture ratio. In such case, it is desirable, at the zoomingoperation from the wide angle end to the telephoto end, to increase thedistance between the third and fourth lens groups and to decrease thedistance between the fourth and fifth lens groups.

A third object of the present invention is to provide a zoom lens inwhich, even in the use of the inner focusing method, the amount ofmovement of the focusing lens group required for focusing to the objectof a given distance remains substantially constant regardless of thefocal length of the zoom lens.

The above-mentioned third object can be attained, according to thepresent invention, by a zoom lens provided, in the order from the objectside, with a first lens group consisting of a negative meniscus lensconvex to the object side, a negative lens and a positive lens andhaving a negative refractive power in the entire group, a second lensgroup of a positive refractive power, and a third lens group of apositive refractive power, wherein, at the zooming operation from thewide angle end to the telephoto end, the distance between the first andsecond lens groups decreases, while that between the second and thirdlens groups varies and the following conditions are satisfied:

    1<|f1|/fw<1.5(f1<0)                      (3-1)

    0.5<f2/f3<2                                                (3-2)

wherein

fw: focal length of the entire lens system at the wide angle end;

f1: focal length of the first lens group;

f2: focal length of the second lens group; and

f3: focal length of the third lens group.

Also, there is provided a configuration provided, in the order from theobject side, with a first lens group of a negative refractive power, asecond lens group of a positive refractive power, and a third lens groupof a positive refractive power, wherein, at the zooming operation fromthe wide angle end to the telephoto end, the distance between the firstand second lens groups decreases, while that between the second andthird lens groups varies, and the following conditions are satisfied:

    1<|f1|/fw<1.5(f1<0)                      (3-1)

    0.5<f2/f3<2                                                (3-2)

    0.8<x2/x3<1.2                                              (3-3)

wherein

fw: focal length of the entire system at the wide angle end;

f1: focal length of the first lens group;

f2: focal length of the second lens group;

f3: focal length of the third lens group;

x2: amount of zooming movement, from the wide angle end to the telephotoend, of the second lens group relative to the image plane; and

x3: amount of zooming movement, from the wide angle end to the telephotoend, of the third lens group relative to the image plane.

The above-mentioned configurations preferably satisfy at least one ofthe following conditions:

    f2/(|f1|+e1t)>0.8                        (3-4)

    f2/(|f1|+e1w)<1.2                        (3-5)

    |β2t|>2                             (3-6)

    |β2w|>2                             (3-7)

    β2t>2                                                 (3-8)

    β2w<-2                                                (3-9)

wherein

β2t: imaging magnification of the second lens group at the telephotoend;

β2w: imaging magnification of the second lens group at the wide angleend;

fw: focal length of the entire system at the wide angle end;

f1: focal length of the first lens group;

f2: focal length of the second lens group;

f3: focal length of the third lens group;

e1w: distance from the image-side principal point of the first lensgroup to the object-side principal point of the second lens group at thewide angle end; and

e1t: distance from the image-side principal point of the first lensgroup to the object-side principal point of the second lens group at thetelephoto end.

Also, in the case of the zoom lens consisting of a negative first lensgroup, a positive second lens group and a positive third lens group, thefollowing conditions are preferably satisfied:

    f3/e3w>0.8                                                 (3-10)

    f3/e3t>1.2                                                 (3-11)

wherein

e3w: distance from the image-side principal point of the third lensgroup to the image plane at the wide angle end;

e3t: distance from the image-side principal point of the third lensgroup to the image plane at the telephoto end.

The above-mentioned zoom lens, attaining the third object of the presentinvention, is provided, in the order from the object side, with anegative first lens group, a positive second lens group and a positivethird lens group, wherein the second lens group is given a large imagingmagnification in the entire zooming range from the wide angle end to thetelephoto end.

In such configuration, in effecting the focusing by the movement of thesecond lens group toward the image plane, the amount Δ of focusingmovement of the second lens group can be approximated by:

    Δ1≅{β.sup.2 /(β.sup.2 -1)}·{f1.sup.2 /(D0-f1)}                                                 (3-12)

wherein

β: imaging magnification of the second lens group;

f1: focal length of the first lens group;

D0: distance from the object point to the object-side principal point ofthe first lens group.

The f1 in the right-hand term of the equation (3-12) is a constant, andD0 becomes substantially constant if the variation in the entire lengthby zooming is small in comparison with the phototaking distance. On theother hand, β varies in the zooming, but, if given a large absolutevalue, {β² /(β² -1)} approaches 1 and varies little in the zooming.

Based on these facts, |β| has to be made large in order to decrease thevariation, in the zooming, of the amount of the focusing movement of thesecond lens group. It is also desirable that D0 does not vary, or thefirst lens group does not move, in the zooming operation.

Also, as will be apparent from the equation (3-12), a smaller value of|f1| decreases the amount of focusing movement of the second lens groupand also allows for decreasing the variation, by the zooming, in theamount of focusing movement of the second lens group.

The condition (3-1) defines the appropriate focal length for the firstlens group. Above the upper limit of the condition (3-1), the entirelens length becomes difficult to decrease. Also in case of focusing bythe movement of the second lens group toward the image plane, it isdesirable to satisfy the upper limit of the condition (3-1), in order todecrease the variation, by the zooming, in the amount of focusingmovement of the second lens group and to decrease the amount of focusingmovement of the second lens group. Also the decrease of the amount offocusing movement of the second lens group is effective for decreasingthe variations in the aberrations by the focusing operation. On theother hand, below the lower limit of the condition (3-1), the negativedistortion aberration increases undesirably at the wide angle end.

The condition (3-2) defines the appropriate ratio of the focal lengthsof the second and third lens groups. Below the lower limit of thecondition (3-2), the refractive power of the second lens group increasesand the spherical aberration becomes difficult to correct. On the otherhand, above the upper limit of the condition (3-2), it becomes difficultto secure the back focus length and to decrease the entire length of thezoom lens.

Also, the condition (3-3) defines the appropriate ratio of the amountsof zooming movement of the second and third lens groups from the wideangle end to the telephoto end. Below the lower limit of the condition(3-3), the distance between the second and third lens groups increasesat the wide angle end, whereby the compactization becomes difficult andthe distortion and other off-axial aberrations become difficult tocorrect. On the other hand, above the upper limit of the condition(3-3), the entire lens length increases at the telephoto end and thedistance D0 from the object point to the object-side principal point ofthe first lens group at the telephoto end becomes small in comparisonwith D0 at the wide angle end. This fact leads, as indicated by theequation (3-12), to an undesirable increase of the variation, in thezooming, of the amount of focusing movement of the second lens group.

The conditions (3-4) and (3-5) define the appropriate relationshipbetween the focal lengths of the first and second lens group. Below thelower limit of the condition (3-4) or above the upper limit of thecondition (3-5), the variation, by the zooming, in the amount offocusing movement of the second lens group increases undesirably.

The conditions (3-6) and (3-7) define the value of |β| at the wide angleend and at the telephoto end. Below the lower limits of the conditions(3-6) and (3-7), the variation, by the zooming, in the amount offocusing movement of the second lens group increase, undesirably. Theabove-mentioned variation can be decreased further by taking "3" as thelower limit of the conditions (3-6) and (3-7).

By selecting substantially same values for |β| at the wide angle end andat the telephoto end, the amount of focusing movement of the second lensgroup can be made approximately the same at the wide angle end and atthe telephoto end. For achieving efficient zooming, in such case, it isdesirable to select the imaging magnification β2w of the second lensgroup at the wide angle end as negative and the imaged magnification β2tat the telephoto end as positive, and preferably to satisfy theconditions (3-8) and (3-9).

The conditions (3-10) and (3-11) define, in the zoom lens consisting ofa negative first lens group, a positive second lens group and a positivethird lens group, the appropriate range of the focal length of the thirdlens group in case the focusing is effected by the second lens group.Below the lower limit of the condition (3-10) or above the upper limitof the condition (3-11), the variation, by the zooming, in the amount offocusing movement of the second lens group increases undesirably.

It is also possible to fix the first lens group, by using the second orthird lens group as a compensator. In such case, it is effective fordecreasing the entire lens length if, at the zooming from the wide angleend to the telephoto end, the distance between the second and third lensgroups increases in the vicinity of the wide angle end and decreases inthe vicinity of the telephoto end.

Also, in the case of focusing with the second lens group, in order todecrease the variation of the aberrations by the zooming, the secondlens group is preferably composed of an cemented positive lens and anegative meniscus lens convex to the object side.

Also, the first lens group composed, in the order from the object side,of a negative meniscus lens convex to the object side, a negative lensand positive lens is effective for satisfactory aberrations with arelatively simple structure. Furthermore, the addition of a positivelens at the object side of the above-mentioned negative meniscus lens isparticularly effective for correcting the distortion aberration at thewide angle end, thus for achieving a wide image angle.

Furthermore, inclusion of at least an aspherical lens in the first lensgroup is effective for correcting the astigmatism, particularly at thewide angle end.

Also, the third lens group composed, in the order from the object side,of a positive lens, a negative lens and a positive lens is effective forcorrecting the spherical aberration over the entire focal length rangewith a relatively simple structure.

Furthermore, a diaphragm is preferably provided between the second andthird lens groups, in order to satisfactorily correct the aberrationsover the entire focal length range from the wide angle end to thetelephoto end.

The present invention is based on a 3-group zoom lens consisting of anegative first lens group, a positive second lens group and a positivethird lens group, but a positive or negative fourth lens group may beadded at the image side of the above-mentioned 3-group zoom lens, forincreasing the aperture ratio or reducing the dimension.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are views showing the configuration of an embodiment 1of the present invention;

FIGS. 2A to 2C are aberration charts of the embodiment 1 at the wideangle end and at a phototaking distance R=inf.;

FIGS. 3A to 3C are aberration charts of the embodiment 1 at thetelephoto end and at a phototaking distance R=inf.;

FIGS. 4A to 4C are aberration charts of the embodiment 1 at the wideangle end and at a phototaking distance R=500;

FIGS. 5A to 5C are aberration charts of the embodiment 1 at thetelephoto end and at a phototaking distance R=500;

FIGS. 6A and 6B are views showing the configuration of an embodiment 2of the present invention;

FIGS. 7A to 7C are aberration charts of the embodiment 2 at the wideangle end and at a phototaking distance R=inf.;

FIGS. 8A to 8C are aberration charts of the embodiment 2 at thetelephoto end and at a phototaking distance R=inf.;

FIGS. 9A to 9C are aberration charts of the embodiment 2 at the wideangle end and at a phototaking distance R=500;

FIGS. 10A to 10C are aberration charts of the embodiment 2 at thetelephoto end and at a phototaking distance R=500;

FIGS. 11A and 11B are views showing the configuration of an embodiment 3of the present invention;

FIGS. 12A to 12C are aberration charts of the embodiment 3 at the wideangle end and at a phototaking distance R=inf.;

FIGS. 13A to 13C are aberration charts of the embodiment 3 at thetelephoto end and at a phototaking distance R=inf.;

FIGS. 14A to 14C are aberration charts of the embodiment 3 at the wideangle end and at a phototaking distance R=500;

FIGS. 15A to 15C are aberration charts of the embodiment 3 at thetelephoto end and at a phototaking distance R=500;

FIGS. 16A and 16B are views showing the configuration of an embodiment 4of the present invention;

FIGS. 17A to 17C are aberration charts of the embodiment 4 at the wideangle end and at a phototaking distance R=inf.;

FIGS. 18A to 18C are aberration charts of the embodiment 4 at thetelephoto end and at a phototaking distance R=inf.;

FIGS. 19A to 19C are aberration charts of the embodiment 4 at the wideangle end and at a phototaking distance R=500;

FIGS. 20A to 20C are aberration charts of the embodiment 4 at thetelephoto end and at a phototaking distance R=500;

FIGS. 21A and 21B are views showing the configuration of an embodiment 5of the present invention;

FIGS. 22A to 22C are aberration charts of the embodiment 5 at the wideangle end and at a phototaking distance R=inf.;

FIGS. 23A to 23C are aberration charts of the embodiment 5 at thetelephoto end and at a phototaking distance R=inf.;

FIGS. 24A to 24C are aberration charts of the embodiment 5 at the wideangle end and at a phototaking distance R=500;

FIGS. 25A to 25C are aberration charts of the embodiment 5 at thetelephoto end and at a phototaking distance R=500;

FIGS. 26A and 26B are views showing the configuration of an embodiment 6of the present invention;

FIGS. 27A to 27C are aberration charts of the embodiment 6 at the wideangle end and at a phototaking distance R=inf.;

FIGS. 28A to 28C are aberration charts of the embodiment 6 at thetelephoto end and at a phototaking distance R=inf.;

FIGS. 29A to 29C are aberration charts of the embodiment 6 at the wideangle end and at a phototaking distance R=500;

FIGS. 30A to 30C are aberration charts of the embodiment 6 at thetelephoto end and at a phototaking distance R=500;

FIGS. 31A and 31B are views showing the configuration of an embodiment 9of the present invention;

FIGS. 32A to 32C are aberration charts of the embodiment 9 at the wideangle end and at a phototaking distance R=inf.;

FIGS. 33A to 33C are aberration charts of the embodiment 9 at thetelephoto end and at a phototaking distance R=inf.;

FIGS. 34A to 34C are aberration charts of the embodiment 9 at the wideangle end and at a phototaking distance R=500;

FIGS. 35A to 35C are aberration charts of the embodiment 9 at thetelephoto end and at a phototaking distance R=500;

FIGS. 36A and 36B are views showing the configuration of an embodiment10 of the present invention;

FIGS. 37A to 37C are aberration charts of the embodiment 10 at the wideangle end and at a phototaking distance R=inf.;

FIGS. 38A to 38C are aberration charts of the embodiment 10 at thetelephoto end and at a phototaking distance R=inf.;

FIGS. 39A to 39C are aberration charts of the embodiment 10 at the wideangle end and at a phototaking distance R=500;

FIGS. 40A to 40C are aberration charts of the embodiment 10 at thetelephoto end and at a phototaking distance R=500;

FIGS. 41A and 41B are views showing the configuration of an embodiment11 of the present invention;

FIGS. 42A to 42C are aberration charts of the embodiment 11 at the wideangle end and at a phototaking distance R=inf.;

FIGS. 43A to 43C are aberration charts of the embodiment 11 at thetelephoto end and at a phototaking distance R=inf.;

FIGS. 44A to 44C are aberration charts of the embodiment 11 at the wideangle end and at a phototaking distance R=500;

FIGS. 45A to 45C are aberration charts of the embodiment 11 at thetelephoto end and at a phototaking distance R=500;

FIGS. 46A and 46B are views showing the configuration of an embodiment12 of the present invention;

FIGS. 47A to 47C are aberration charts of the embodiment 12 at the wideangle end and at a phototaking distance R=inf.;

FIGS. 48A to 48C are aberration charts of the embodiment 12 at thetelephoto end and at a phototaking distance R=inf.;

FIGS. 49A to 49C are aberration charts of the embodiment 12 at the wideangle end and at a phototaking distance R=500;

FIGS. 50A to 50C are aberration charts of the embodiment 12 at thetelephoto end and at a phototaking distance R=500;

FIGS. 51A and 51B are views showing the configuration of an embodiment13 of the present invention;

FIGS. 52A to 52C are aberration charts of the embodiment 13 at the wideangle end and at a phototaking distance R=inf.;

FIGS. 53A to 53C are aberration charts of the embodiment 13 at thetelephoto end and at a phototaking distance R=inf.;

FIGS. 54A to 54C are aberration charts of the embodiment 13 at the wideangle end and at a phototaking distance R=500;

FIGS. 55A to 55C are aberration charts of the embodiment 13 at thetelephoto end and at a phototaking distance R=500;

FIGS. 56A and 56B are views showing the configuration of an embodiment14 of the present invention;

FIGS. 57A to 57C are aberration charts of the embodiment 14 at the wideangle end and at a phototaking distance R=inf.;

FIGS. 58A to 58C are aberration charts of the embodiment 14 at thetelephoto end and at a phototaking distance R=inf.;

FIGS. 59A to 59C are aberration charts of the embodiment 14 at the wideangle end and at a phototaking distance R=500;

FIGS. 60A to 60C are aberration charts of the embodiment 14 at thetelephoto end and at a phototaking distance R=500;

FIGS. 61A and 61B are views showing the configuration of an embodiment15 of the present invention;

FIGS. 62A to 62C are aberration charts of the embodiment 15 at the wideangle end and at a phototaking distance R=inf.;

FIGS. 63A to 63C are aberration charts of the embodiment 15 at thetelephoto end and at a phototaking distance R=inf.;

FIGS. 64A to 64C are aberration charts of the embodiment 15 at the wideangle end and at a phototaking distance R=500;

FIGS. 65A to 65C are aberration charts of the embodiment 15 at thetelephoto end and at a phototaking distance R=500;

FIGS. 66A and 66B are views showing the configuration of an embodiment16 of the present invention;

FIGS. 67A to 67C are aberration charts of the embodiment 16 at the wideangle end and at a phototaking distance R=inf.;

FIGS. 68A to 68C are aberration charts of the embodiment 16 at thetelephoto end and at a phototaking distance R=inf.;

FIGS. 69A to 69C are aberration charts of the embodiment 16 at the wideangle end and at a phototaking distance R=500;

FIGS. 70A to 70C are aberration charts of the embodiment 16 at thetelephoto end and at a phototaking distance R=500;

FIGS. 71A and 71B are views showing the configuration of an embodiment17 of the present invention;

FIGS. 72A to 72C are aberration charts of the embodiment 17 at the wideangle end and at a phototaking distance R=inf.;

FIGS. 73A to 73C are aberration charts of the embodiment 17 at thetelephoto end and at a phototaking distance R=inf.;

FIGS. 74A to 74C are aberration charts of the embodiment 17 at the wideangle end and at a phototaking distance R=500;

FIGS. 75A to 75C are aberration charts of the embodiment 17 at thetelephoto end and at a phototaking distance R=500;

FIGS. 76A and 76B are views showing the configuration of an embodiment19 of the present invention;

FIGS. 77A to 77C are aberration charts of the embodiment 19 at the wideangle end and at a phototaking distance R=inf.;

FIGS. 78A to 78C are aberration charts of the embodiment 19 at thetelephoto end and at a phototaking distance R=inf.;

FIGS. 79A to 79C are aberration charts of the embodiment 19 at the wideangle end and at a phototaking distance R=500;

FIGS. 80A to 80C are aberration charts of the embodiment 19 at thetelephoto end and at a phototaking distance R=500;

FIGS. 81A and 81B are views showing the configuration of an embodiment21 of the present invention;

FIGS. 82A to 82C are aberration charts of the embodiment 21 at the wideangle end and at a phototaking distance R=inf.;

FIGS. 83A to 83C are aberration charts of the embodiment 21 at thetelephoto end and at a phototaking distance R=inf.;

FIGS. 84A to 84C are aberration charts of the embodiment 21 at the wideangle end and at a phototaking distance R=500; and

FIGS. 85A to 85C are aberration charts of the embodiment 21 at thetelephoto end and at a phototaking distance R=500.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now the present invention will be described in greater detail byreference to preferred embodiments thereof.

[Embodiment 1]

FIGS. 1A and 1B are views showing the configuration of the zoom lens ofan embodiment 1, respectively at the wide angle end and at the telephotoend. The zoom lens is composed, in the order from the object side, of anegative first lens group G1, a positive second lens group G2, apositive third lens group G3, a negative fourth lens group G4 and apositive fifth lens group G5, wherein, at the zooming from the wideangle end to the telephoto end, the first lens group remains fixed whilethe second to fifth lens groups move toward the object side, the air gapbetween the first and second lens groups decreases, that between thesecond and third lens groups and that between the third and fourth lensgroups both increase, and that between the fourth and fifth lens groupsdecreases.

The focusing from a long object distance to a short object distance isexecuted by a movement of the second lens group toward the image plane.

The lens face, closest to the object side, in the first lens group is anaspherical face, the shape of which is given by:

    X(y)=y.sup.2 /[r·{1+(1-k·y.sup.2 /r.sup.2).sup.1/2 }]+C2·y.sup.2 +C4·y.sup.4 +C6·y.sup.6 +C8·y.sup.8 +C10·y.sup.10

wherein X(y) is the axial distance from a tangential plane at the vertexof the aspherical face to a point of a height y on the aspherical face,r is the radius of paraxial curvature, k is the conical constant, and Ciis the i-th order aspherical coefficient.

The following Table 1 shows the parameters of the embodiment 1 of thepresent invention, wherein f is the focal length, F is the F-number, and2ω is the image angle. The numbers in the left-hand column indicate theorder from the object side, r indicates the radius of curvature of thelens face, d is the distance between the lens faces, n and ν are therefractive index and the Abbe's number for d-line (λ=587.6 nm). R in thetable of variable distances indicates the phototaking distance.

                  TABLE 1                                                         ______________________________________                                        f = 20.50-24.00-28.00-34.00                                                   F/2.88                                                                        2ω = 95.36-84.20-74.79-64.41°                                    r             d           ν   n                                            ______________________________________                                        1       42.8646   2.5000      49.5 1.77279                                    2       19.0563   12.2538                                                     3       -89.7386  2.0000      47.5 1.78797                                    4       43.6226   3.0774                                                      5       -1278.6770                                                                              2.7808      31.6 1.75692                                    6       -114.4184 0.2000                                                      7       37.2342   3.5000      31.6 1.75692                                    8       70.6430   (d8)                                                        9       58.7658   1.2000      29.5 1.71736                                    10      27.8095   7.7426      70.0 1.51860                                    11      -62.9952  (d11)                                                       12      40.9312   2.9396      53.9 1.71300                                    13      178.2683  (d13)                                                       14      (diaphragm)                                                                             2.0000                                                      15      -40.2685  1.2000      52.3 1.74810                                    16      28.7416   3.3073      25.4 1.80518                                    17      203.9851  (d17)                                                       18      59.1968   3.8000      50.8 1.65844                                    19      -63.0449  1.5000                                                      20      79.5746   2.0000      26.1 1.78470                                    21      30.6815   1.8153                                                      22      121.6247  3.3377      45.4 1.79668                                    23      -76.5204  0.2000                                                      24      275.3981  6.1577      57.0 1.62280                                    25      -21.9059  1.7000      23.0 1.86074                                    26      -60.5026                                                              ______________________________________                                    

Aspherical coefficients of first face:

k=1.0000

C2=0.0000

C4=3.9551E-6

C6=7.4971E-9

C8=-1.2898E-11

C11=2.0419E-14

    ______________________________________                                        Table of variable distances:                                                  ______________________________________                                        f       20.50    24.00       28.00  34.00                                     R       inf      inf         inf    inf                                       d8      19.53510 12.68258    7.15140                                                                              1.00000                                   d11     3.53475  7.61249     9.66310                                                                              9.97063                                   d13     1.54528  4.05890     7.08276                                                                              9.83202                                   d17     9.73143  7.26988     4.61998                                                                              2.00000                                   f       20.50    24.00       28.00  34.00                                     R       500.00   500.00      500.00 500.00                                    d8      22.07078 15.26240    9.79958                                                                              3.76429                                   d11     0.99907  5.03267     7.01491                                                                              7.20634                                   d13     1.54528  4.05890     7.08276                                                                              9.83202                                   d17     9.73143  7.26988     4.61998                                                                              2.00000                                   ______________________________________                                    

Values corresponding to the conditions:

    f2/f3=1.036                                                (1-1)

FIGS. 2A to 2C and 3A to 3C are aberration charts of the embodiment 1 ata phototaking distance R=inf., respectively at the wide angle end and atthe telephoto end, while

FIGS. 4A to 4C and 5A to 5C are aberration charts of the embodiment 1 ata phototaking distance R=500, respectively at the wide angle end and atthe telephoto end. In these charts, FNO indicates F-number, NA indicatesnumerical aperture, Y indicates image height, d indicates d-line(λ=587.6 nm) and g indicates g-line (λ=435.6 nm). In the astigmatismchart, the solid line and broken line respectively indicate the sagittaland meridional image planes.

These aberration charts indicate that the present embodiment issatisfactorily corrected for the various aberrations and has excellentimaging performance.

[Embodiment 2]

FIGS. 6A and 6B are views showing the configuration of the zoom lens ofan embodiment 2, respectively at the wide angle end and at the telephotoend. The zoom lens is composed, in the order from the object side, of anegative first lens group G1, a positive second lens group G2, apositive third lens group G3, a negative fourth lens group G4 and apositive fifth lens group G5, wherein, at the zooming from the wideangle end to the telephoto end, the first lens group remains fixed whilethe second to fifth lens groups move toward the object side, the air gapbetween the first and second lens groups decreases, that between thesecond and third lens groups and that between the third and fourth lensgroups both increase, and that between the fourth and fifth lens groupsdecreases.

The focusing from a long object distance to a short object distance isexecuted by a movement of the second lens group toward the image plane.

The lens face, closest to the object side, in the first lens group is anaspherical face, the shape of which is given by:

    X(y)=y.sup.2 /[r·{1+(1-k·y.sup.2 /r.sup.2).sup.1/2 }]+C2·y.sup.2 +C4·y.sup.4 +C6·y.sup.6 +C8·y.sup.8 +C10·y.sup.10

wherein X(y) is the axial distance from a tangential plane at the vertexof the aspherical face to a point of a height y on the aspherical face,r is the radius of paraxial curvature, k is the conical constant, and Ciis the i-th order aspherical coefficient.

The following Table 2 shows the parameters of the embodiment 2 of thepresent invention, wherein f is the focal length, F is the F-number and2ω is the image angle. The numbers in the left-hand column indicate theorder from the object side, r indicates the radius of curvature of thelens face, d is the distance between the lens faces, n and ν are therefractive index and the Abbe's number for d-line (λ=587.6 nm). R in thetable of variable distances indicates the phototaking distance.

                  TABLE 2                                                         ______________________________________                                        f = 20.50-24.00-28.00-34.00                                                   F/2.88                                                                        2ω = 95.32-84.13-74.68-64.33°                                    r             d           ν   n                                            ______________________________________                                        1       42.2348   2.5000      49.5 1.77279                                    2       18.6087   12.6784                                                     3       -85.0463  2.0000      47.5 1.78797                                    4       42.8849   3.4377                                                      5       -281.6993 2.8294      31.6 1.75692                                    6       -91.5606  0.2000                                                      7       37.8425   3.5687      31.6 1.75692                                    8       79.7702   (d8)                                                        9       49.3392   1.2000      29.5 1.71736                                    10      25.1981   8.9627      70.0 1.51860                                    11      -57.2394  (d11)                                                       12      38.8324   2.9313      53.9 1.71300                                    13      141.4542  (d13)                                                       14      (diaphragm)                                                                             2.0000                                                      15      -45.2367  1.2000      52.3 1.74810                                    16      25.3136   3.2146      25.4 1.80518                                    17      86.3355   (d17)                                                       18      49.6845   3.7880      50.8 1.65844                                    19      -66.2974  1.5000                                                      20      52.9095   2.0000      26.1 1.78470                                    21      26.8530   1.9865                                                      22      134.4554  2.8736      45.4 1.79668                                    23      -107.7591 0.2000                                                      24      540.8718  5.9855      57.0 1.62280                                    25      -19.9107  1.7000      23.0 1.86074                                    26      -49.3725                                                              ______________________________________                                    

Aspherical coefficients of first

k=1.0000

C2=0.0000

C4=3.9665E-6

C6=7.7825E-9

C8=-1.3483E-11

C10=2.1699E-14

    ______________________________________                                        Table of variable distances:                                                  ______________________________________                                        f       20.50    24.00       28.00  34.00                                     R       inf      inf         inf    inf                                       d8      19.81245 13.19465    7.54540                                                                              1.00000                                   d11     3.53277  8.03935     10.95058                                                                             12.18067                                  d13     1.30000  3.06781     5.05089                                                                              6.45949                                   d17     9.12737  6.88872     4.40569                                                                              2.00000                                   f       20.50    24.00       28.00  34.00                                     R       500.00   500.00      500.00 500.00                                    d8      22.34554 15.67965    10.03095                                                                             3.53360                                   d11     0.99968  5.55435     8.46503                                                                              9.64707                                   d13     1.30000  3.06781     5.05089                                                                              6.45949                                   d17     9.12737  6.88872     4.40569                                                                              2.00000                                   ______________________________________                                    

Values corresponding to the conditions:

    f2/f3=0.879                                                (1-1)

FIGS. 7A to 7C and 8A to 8C are aberration charts of the embodiment 2 ata phototaking distance R=inf., respectively at the wide angle end and atthe telephoto end, while FIGS. 9A to 9C and 10A to 10C are aberrationcharts of the embodiment 2 at a phototaking distance R=500, respectivelyat the wide angle end and at the telephoto end. In these charts, FNOindicates F-number, NA indicates numerical aperture, Y indicates imageheight, d indicates d-line (λ=587.6 nm) and g indicates g-line (λ=435.6nm). In the astigmatism chart, the solid line and broken linerespectively indicate the sagittal and meridional image planes.

These aberration charts indicate that the present embodiment issatisfactorily corrected for the various aberrations and has excellentimaging performance.

[Embodiment 3]

FIGS. 11A and 11B are views showing the configuration of the zoom lensof an embodiment 3, respectively at the wide angle end and at thetelephoto end. The zoom lens is composed, in the order from the objectside, of a negative first lens group G1, a positive second lens groupG2, a positive third lens group G3, a negative fourth lens group G4 anda positive fifth lens group G5, wherein, at the zooming from the wideangle end to the telephoto end, the first lens group at first movestoward the image plane and then toward the object side, while the secondto fifth lens groups move toward the object side, the air gap betweenthe first and second lens groups decreases, that between the second andthird lens groups and that between the third and fourth lens groups bothincrease, and that between the fourth and fifth lens groups decreases.

The focusing from a long object distance to a short object distance isexecuted by a movement of the second lens group toward the image plane.

The lens face, closest to the object side, in the first lens group is anaspherical face, the shape of which is given by:

    X(y)=y.sup.2 /[r·{1+(1-k·y.sup.2 /r.sup.2).sup.1/2 }]+C2·y.sup.2 +C4·y.sup.4 +C6·y.sup.6 +C8·y.sup.8 +C10·y.sup.10

wherein X(y) is the axial distance from a tangential plane at the vertexof the aspherical face to a point of a height y on the aspherical face,r is the radius of paraxial curvature, k is the conical constant, and Ciis the i-th order aspherical coefficient.

The following Table 3 shows the parameters of the embodiment 3 of thepresent invention, wherein f is the focal length, F is the F-number and2ω is the image angle. The numbers in the left-hand column indicate theorder from the object side, r indicates the radius of curvature of thelens face, d is the distance between the lens faces, n and ν are therefractive index and the Abbe's number for d-line (λ=587.6 nm). R in thetable of variable distances indicates the phototaking distance.

                  TABLE 3                                                         ______________________________________                                        f = 20.50-24.00-28.00-34.00                                                   F/2 2.88                                                                      2ω = 95.35-85.14-75.16-64.32°                                    r             d           ν   n                                            ______________________________________                                        1       42.2787   2.5000      49.5 1.77279                                    2       18.5956   12.8205                                                     3       -83.4503  2.0000      47.5 1.78797                                    4       43.6860   3.3554                                                      5       -313.6719 2.6689      31.6 1.75692                                    6       -98.0620  0.2000                                                      7       37.0798   3.6299      31.6 1.75692                                    8       78.4894   (d8)                                                        9       49.4652   1.2000      29.5 1.71736                                    10      24.3696   9.9505      70.0 1.51860                                    11      -57.4190  (d11)                                                       12      39.5690   2.8332      53.9 1.71300                                    13      126.0564  (d13)                                                       14      (diaphragm)                                                                             2.0000                                                      15      -39.3369  1.2000      52.3 1.74810                                    16      25.9580   3.2949      25.4 1.80518                                    17      115.5584  (d17)                                                       18      55.1843   4.2195      50.8 1.65844                                    19      -54.8544  1.5000                                                      20      48.3880   2.0000      26.1 1.78470                                    21      27.2065   2.0504                                                      22      157.1203  2.7578      45.4 1.79668                                    23      -119.4629 0.2000                                                      24      319.2649  6.1314      57.0 1.62280                                    25      -19.7617  1.7000      23.0 1.86074                                    26      -51.3296                                                              ______________________________________                                    

Aspherical coefficients of first face:

k=1.0000

C2=0.0000

C4=4.1617E-6

C6=7.6785E-9

C8=-1.3588E-11

C10=2.2624E-14

    ______________________________________                                        Table of variable distances:                                                  ______________________________________                                        f       20.50    24.00       28.00  34.00                                     R       inf      inf         inf    inf                                       d8      18.54847 12.02987    6.96334                                                                              1.00000                                   d11     3.49271  3.02353     6.52852                                                                              11.09590                                  d13     1.30000  3.89859     6.19148                                                                              7.83521                                   d17     9.14416  7.61705     5.08422                                                                              2.00000                                   f       20.50    24.00       28.00  34.00                                     R       500.00   500.00      500.00 500.00                                    d8      21.04149 14.47691    9.43263                                                                              3.54552                                   d11     0.99969  0.57649     4.05923                                                                              8.55038                                   d13     1.30000  3.89859     6.19148                                                                              7.83521                                   d17     9.14416  7.61705     5.08422                                                                              2.00000                                   ______________________________________                                    

Values corresponding to the conditions:

    f2/f3=0.836                                                (1-1)

FIGS. 12A to 12C and 13A to 13C are aberration charts of the embodiment3 at a phototaking distance R=inf., respectively at the wide angle endand at the telephoto end, while FIGS. 14A to 14C and 15A to 15C areaberration charts of the embodiment 3 at a phototaking distance r=500,respectively at the wide angle end and at the telephoto end. In thesecharts, FNO indicates F-number, NA indicates numerical aperture, Yindicates image height, d indicates d-line (λ=587.6 nm) and g indicatesg-line (λ=435.6 nm). In the astigmatism chart, the solid line and brokenline respectively indicate the sagittal and meridional image planes.

These aberration charts indicate that the present embodiment issatisfactorily corrected for the various aberrations and has excellentimaging performance.

[Embodiment 4]

FIGS. 16A and 16B are views showing the configuration of the zoom lensof an embodiment 4, respectively at the wide angle end and at thetelephoto end. The zoom lens is composed, in the order from the objectside, of a negative first lens group G1, a positive second lens groupG2, a positive third lens group G3, a negative fourth lens group G4 anda positive fifth lens group GS, wherein, at the zooming from the wideangle end to the telephoto end, the first lens group remains fixed whilethe second to fifth lens groups move toward the object side, in whichthe third and fifth lens groups move integrally, the air gap between thefirst and second lens groups decreases, that between the second andthird lens groups and that between the third and fourth lens groups bothincrease, and that between the fourth and fifth lens groups decreases.

The focusing from a long object distance to a short object distance isexecuted by a movement of the second lens group toward the image plane.

The lens face, closest to the object side, in the first lens group is anaspherical face, the shape of which is given by:

    X(y)=y.sup.2 /[r·{1+(1-k·y.sup.2 /r.sup.2).sup.1/2 }]+C2·y.sup.2 +C4·y.sup.4 +C6·y.sup.6 +C8·y.sup.8 +C10·y.sup.10

wherein X(y) is the axial distance from a tangential plane at the vertexof the aspherical face to a point of a height y on the aspherical face,r is the radius of paraxial curvature, k is the conical constant, and Ciis the i-th order aspherical coefficient.

The following Table 4 shows the parameters of the embodiment 4 of thepresent invention, wherein f is the focal length, F is the F-number and2ω is the image angle. The numbers in the left-hand column indicate theorder from the object side, r indicates the radius of curvature of thelens face, d is the distance between the lens faces, n and ν are therefractive index and the Abbe's number for d-line (λ=587.6 nm). R in thetable of variable distances indicates the phototaking distance.

                  TABLE 4                                                         ______________________________________                                        f = 20.50-24.00-28.00-34.00                                                   F/2.88                                                                        2ω = 95.35-85.18-74.16-64.34°                                    r             d           ν   n                                            ______________________________________                                        1       42.9194   2.5000      49.5 1.77279                                    2       18.7365   12.6821                                                     3       -82.5205  2.0000      47.5 1.78797                                    4       43.4952   3.4977                                                      5       -238.6736 2.7663      31.6 1.75692                                    6       -83.8838  0.2000                                                      7       38.0192   3.5274      31.6 1.75692                                    8       77.9821   (d8)                                                        9       48.0044   1.2000      29.5 1.71736                                    10      24.7177   9.0251      70.0 1.51860                                    11      -58.6904  (d11l)                                                      12      40.7663   2.7567      53.9 1.71300                                    13      118.4476  (d13)                                                       14      (diaphragm)                                                                             2.0000                                                      15      -40.4319  1.2000      52.3 1.74810                                    16      28.4761   3.2720      25.4 1.80518                                    17      189.1119  (d17)                                                       18      57.0051   3.7547      50.8 1.65844                                    19      -58.5179  1.5000                                                      20      56.2881   2.0000      26.1 1.78470                                    21      27.4966   1.8584                                                      22      117.3432  2.9130      45.4 1.79668                                    23      -113.2325 0.2000                                                      24      618.0544  5.9171      57.0 1.62280                                    25      -19.9986  1.7000      23.0 1.86074                                    26      -51.7194                                                              ______________________________________                                    

Aspherical coefficients of first face:

k=1.0000

C2=0.0000

C4=4.0841E-6

C6=7.8040E-9

C8=-1.3893E-11

C10=2.1905E-14

    ______________________________________                                        Table of variable distances:                                                  ______________________________________                                        f       20.50    24.00       28.00  34.00                                     R       inf      inf         inf    inf                                       d8      19.64565 13.03788    7.41693                                                                              1.06090                                   d11     3.52598  7.52908     9.88906                                                                              10.32421                                  d13     1.30000  3.48108     5.93295                                                                              8.33028                                   d17     9.03027  6.84919     4.39732                                                                              2.00000                                   f       20.50    24.00       28.00  34.00                                     R       500.00   500.00      500.00 500.00                                    d8      22.17212 15.51720    9.89740                                                                              3.58791                                   d11     0.99950  5.04976     7.40860                                                                              7.79719                                   d13     1.30000  3.48108     5.93295                                                                              8.33028                                   d17     9.03027  6.84919     4.39732                                                                              2.00000                                   ______________________________________                                    

Values corresponding to the conditions:

    f2/f3=0.758                                                (1-1)

FIGS. 17A to 17C and 18A to 18C are aberration charts of the embodiment4 at a phototaking distance R=inf., respectively at the wide angle endand at the telephoto end, while FIGS. 19A to 19C and 20A to 20C areaberration charts of the embodiment 4 at a phototaking distance R=500,respectively at the wide angle end and at the telephoto end. In thesecharts, FNO indicates F-number, NA indicates numerical aperture, Yindicates image height, d indicates d-line (λ=587.6 nm) and g indicatesg-line (λ=435.6 nm). In the astigmatism chart, the solid line and brokenline respectively indicate the sagittal and meridional planes.

These aberration charts indicate that the present embodiment issatisfactorily corrected for the various aberrations and has excellentimaging performance.

[Embodiment 5]

FIGS. 21A and 21B are views showing the configuration of the zoom lensof an embodiment 5, respectively at the wide angle end and at thetelephoto end. The zoom lens is composed, in the order from the objectside, of a negative first lens group G1, a positive second lens groupG2, a positive third lens group G3, a negative fourth lens group G4 anda positive fifth lens group G5, wherein, at the zooming from the wideangle end to the telephoto end, the first and fourth lens group remainfixed while the second, third and fifth lens groups move toward theobject side, in which the third and fifth lens groups move integrally,the air gap between the first and second lens groups decreases, thatbetween the second and third lens groups and that between the third andfourth lens groups both increase, and that between the fourth and fifthlens groups decreases.

The focusing from a long object distance to a short object distance isexecuted by a movement of the second lens group toward the image plane.

The lens face, closest to the object side, in the first lens group is anaspherical face, the shape of which is given by:

    X(y)=y.sup.2 /[r·{1+(1-k·y.sup.2 /r.sup.2).sup.1/2 }]+C2·y.sup.2 +C4·y.sup.4 +C6·y.sup.6 +C8·y.sup.8 +C10·y.sup.10

wherein X(y) is the axial distance from a tangential plane at the vertexof the aspherical face to a point of a height y on the aspherical face,r is the radius of paraxial curvature, k is the conical constant, and Ciis the i-th order aspherical coefficient.

The following Table 5 shows the parameters of the embodiment 5 of thepresent invention, wherein f is the focal length, F is the F-number and2ω is the image angle. The numbers in the left-hand column indicate theorder from the object side, r indicates the radius of curvature of thelens face, d is the distance between the lens faces, n and ν are therefractive index and the Abbe's number for d-line (λ=587.6 nm). R in thetable of variable distances indicates the phototaking distance.

                  TABLE 5                                                         ______________________________________                                        f = 20.50-24.00-28.00-34.00                                                   F/2.88                                                                        2ω = 95.26-84.00-74.54-63.93°                                    r             d           ν   n                                            ______________________________________                                        1       45.0946   2.5000      49.5 1.77279                                    2       18.5508   12.8994                                                     3       -69.9954  2.0000      47.5 1.78797                                    4       52.6057   3.0830                                                      5       -206.1849 3.0425      31.6 1.75692                                    6       -68.5671  0.2000                                                      7       38.2998   5.4790      31.6 1.75692                                    8       71.0594   (d8)                                                        9       49.2052   1.2000      29.5 1.71736                                    10      25.8105   5.3940      70.0 1.51860                                    11      -60.9739  (d11)                                                       12      50.6519   2.8567      53.9 1.71300                                    13      834.2608  (d13)                                                       14      (diaphragm)                                                                             2.0000                                                      15      -42.6372  1.2000      52.3 1.74810                                    16      34.1340   2.7374      25.4 1.80518                                    17      131.5213  (d17)                                                       18      63.4331   3.8965      50.8 1.65844                                    19      -58.1149  1.5000                                                      20      55.4961   2.0000      26.1 1.78470                                    21      28.4509   2.2469                                                      22      140.8853  2.8147      45.4 1.79668                                    23      -161.0326 0.2000                                                      24      111.3437  6.3885      57.0 1.62280                                    25      -24.7081  1.7000      23.0 1.86074                                    26      -66.6294                                                              ______________________________________                                    

Aspherical coefficients of first face:

k=1.0000

C2=0.0000

C4=3.9675E-6

C6=7.7738E-9

C8=-1.2284E-11

C10=1.8402E-14

    ______________________________________                                        Table of variable distances:                                                  ______________________________________                                        f       20.50    24.00       28.00  34.00                                     R       inf      inf         inf    inf                                       d8      19.41514 12.67603    7.00320                                                                              1.42703                                   d11     3.64652  8.11874     11.05741                                                                             12.60499                                  d13     1.30000  3.56689     6.30106                                                                              10.32964                                  d17     11.29960 9.03271     6.29854                                                                              2.26996                                   f       20.50    24.00       28.00  34.00                                     R       500.00   500.00      500.00 500.00                                    d8      22.06199 15.27809    9.61057                                                                              4.07782                                   d11     0.99967  5.51668     8.45003                                                                              9.95420                                   d13     1.30000  3.56689     6.30106                                                                              10.32964                                  d17     11.29960 9.03271     6.29854                                                                              2.26996                                   ______________________________________                                    

Values corresponding to the conditions:

    f2/f3=0.873                                                (1-1)

FIGS. 22A to 22C and 23A to 23C are aberration charts of the embodiment5 at a phototaking distance R=inf., respectively at the wide angle endand at the telephoto end, while FIGS. 24A to 24C and 25A to 25C areaberration charts of the embodiment 5 at a phototaking distance R=500,respectively at the wide angle end and at the telephoto end. In thesecharts, FNO indicates F-number, NA indicates numerical aperture, Yindicates image height, d indicates d-line (λ=587.6 nm) and g indicatesg-line (λ=435.6 nm). In the astigmatism chart, the solid line and brokenline respectively indicate the sagittal and meridional planes.

These aberration charts indicate that the present embodiment issatisfactorily corrected for the various aberrations, and has excellentimaging performance.

As explained in the foregoing, according to a first aspect of thepresent invention, there can be provided a zoom lens enabling thefocusing in the inner focusing method suitable for auto focusing, whileachieving a wider image angle and a larger aperture ratio. Also, even inthe use of the inner focusing, the amount of movement of the focusinglens group for a given phototaking distance can be made substantiallyconstant for any focal length, so that satisfactory operationperformance can also be attained.

It is furthermore possible to fix the first lens group, therebyimproving the resistance of the zoom lens against mechanical shock,intrusion of waterdrops and dusts.

It is furthermore possible to simplify the structure and to reduce thenumber of components, by fixing the first or fourth lens group, or byintegrally moving the third and fifth lens groups.

[Embodiment 6]

FIGS. 26A and 26B are views showing the configuration of the zoom lensof an embodiment 6, respectively at the wide angle end and at thetelephoto end. The zoom lens is composed, in the order from the objectside, of a negative first lens group G1, a positive second lens group G2and a positive third lens group G3, wherein, at the zooming from thewide angle end to the telephoto end, the first lens group remains fixedwhile the second and third lens groups move toward the object side, theair gap between the first and second lens groups decreases and thatbetween the second and third lens groups increases in the vicinity ofthe wide angle end and decreases in the vicinity of the telephoto end.

The fourth lens face, from the object side, in the first lens group isan aspherical face, the shape of which is given by:

    X(y)=y.sup.2 /[r·{1+(1-k·y.sup.2 /r.sup.2).sup.1/2 }]+C2·y.sup.2 +C4·y.sup.4 +C6·y.sup.6 +C8·y.sup.8 +C10·y.sup.10

wherein X(y) is the axial distance from a tangential plane at the vertexof the aspherical face to a point of a height y on the aspherical face,r is the radius of paraxial curvature, k is the conical constant, and Ciis the i-th order aspherical coefficient.

The focusing from a long object distance to a short object distance isachieved by a movement of the second lens group toward the image plane.

The following Table 6 shows the parameters of the embodiment 6 of thepresent invention, wherein f is the focal length, F is the F-number and2ω is the image angle. The numbers in the left-hand column indicate theorder from the object side, r indicates the radius of curvature of thelens face, d is the distance between the lens faces, n and ν are therefractive index and the Abbe's number for d-line (λ=587.6 nm). R in thetable of variable distances indicates the phototaking distance.

                  TABLE 6                                                         ______________________________________                                        f = 25.50-35.00-48.80                                                         F/4.14-4.70-5.57                                                              2ω = 82.91-63.70-47.79°                                          r             d           ν   n                                            ______________________________________                                        1       208.6765  3.0000      65.4 1.60300                                    2       -623.7782 0.0548                                                      3       210.5357  2.5000      65.4 1.60300                                    4       19.9725   5.5000                                                      5       42.5624   1.2000      45.4 1.79668                                    6       20.4141   5.6000                                                      7       24.8382   4.0000      25.5 1.73038                                    8       53.0935   (d8)                                                        9       1084.4533 1.6000      57.5 1.67025                                    10      -27.9749  0.7000      28.6 1.79504                                    11      -45.7106  (d11)                                                       12      (diaphragm)                                                                             0.2000                                                      13      16.7266   3.0018      38.2 1.65128                                    14      41.3336   1.2876                                                      15      -45.9100  6.1272      28.2 1.74000                                    16      22.3961   1.7690                                                      17      90.0420   3.6026      58.9 1.51823                                    18      -21.8614  0.8623                                                      19      457.3628  4.0430      40.8 1.58144                                    20      -77.1791                                                              ______________________________________                                    

Aspherical coefficients of fourth face:

k=0.9187

C2=0.0000

C4=-7.5000E-6

C6=-1.0998E-8

C8=-9.0408E-12

C10=-1.6277E-13

    ______________________________________                                        Table of variable distances:                                                  ______________________________________                                        f       25.50         35.00    48.80                                          R       inf           inf      inf                                            d8      30.70235      14.23426 0.97971                                        d11     4.48860       12.19658 11.98281                                       f       25.50         35.00    48.80                                          R       500.00        500.00   500.00                                         d8      34.91466      18.27179 5.18155                                        d11     0.27629       8.15905  7.78097                                        ______________________________________                                    

Values corresponding to the conditions:

β2t=5.004

β2w=-4.915

f2/f3=1.208

f2/(|f1|+e1t)=1.250

f2/(|f1|+e1w)=0.831

f3/e3w=1.145

f3/e3t=0.808

FIGS. 27A to 27C and 28A to 28C are aberration charts of the embodiment6 at a phototaking distance R=inf., respectively at the wide angle endand at the telephoto end, while FIGS. 29A to 29C and 30A to 30C areaberration charts of the embodiment 6 at a phototaking distance R=500,respectively at the wide angle end and at the telephoto end. In thesecharts, FNO indicates F-number, NA indicates numerical aperture, Yindicates image height, d indicates d-line (λ=587.6 nm) and g indicatesg-line (λ=435.6 nm). In the astigmatism chart, the solid line and brokenline respectively indicate the sagittal and meridional planes.

These aberration charts indicate that the present embodiment issatisfactorily corrected for the various aberrations, and has excellentimaging performance.

[Embodiment 7]

The zoom lens of the embodiment 7 is the same, in the configuration andthe parameters, as that of the embodiment 1, except for the followingvalues, and the aberration charts are also the same as those of theembodiment 1:

Values corresponding to the conditions:

β2t=3.410

β2w=19.601

f2/f3=1.036

f2/(|f1|+e1t)=1.414

f2/(|f1|+e1w)=1.054

[Embodiment 8]

The zoom lens of the embodiment 8 is the same, in the configuration andthe parameters, as that of the embodiment 2, except for the followingvalues, and the aberration charts are also the same as those of theembodiment 2:

Values corresponding to the conditions:

β2t=6.895

β2w=-6.967

f2/f3=0.879

f2/(|f1|+e1t)=1.170

f2/(|f1|+e1w)=0.874

[Embodiment 9]

FIGS. 31A and 31B are views showing the configuration of the zoom lensof an embodiment 9, respectively at the wide angle end and at thetelephoto end. The zoom lens is composed, in the order from the objectside, of a negative first lens group G1, a positive second lens group G2and a positive third lens group G3, wherein, at the zooming from thewide angle end to the telephoto end, the first lens group remains fixedwhile the second and third lens groups move toward the object side, theair gap between the first and second lens groups decreases and thatbetween the second and third lens groups increases in the vicinity ofthe wide angle end and decreases in the vicinity of the telephoto end.

The fourth lens face, from the object side, in the first lens group isan aspherical face, the shape of which is given by:

    X(y)=y.sup.2 /[r·{1+(1-k·y.sup.2 /r.sup.2).sup.1/2 }]+C2·y.sup.2 +C4·y.sup.4 +C6·y.sup.6 +C8·y.sup.8 +C10·y.sup.10

wherein X(y) is the axial distance from a tangential plane at the vertexof the aspherical face to a point of a height y on the aspherical face,r is the radius of paraxial curvature, k is the conical constant, and Ciis the i-th order aspherical coefficient.

The focusing from a long object distance to a short object distance isachieved by a movement of the second lens group toward the image plane.

The following Table 9 shows the parameters of the embodiment 9 of thepresent invention, wherein f is the focal length, F is the F-number and2ω is the image angle. The numbers in the left-hand column indicate theorder from the object side, r indicates the radius of curvature of thelens face, d is the distance between the lens faces, n and ν are therefractive index and the Abbe's number for d-line (λ=587.6 nm). R in thetable of variable distances indicates the phototaking distance.

                  TABLE 9                                                         ______________________________________                                        f = 36.00-50.00-68.00                                                         F/3.71-4.29-5.05                                                              2ω = 65.26-47.15-35.14°                                          r             d           ν   n                                            ______________________________________                                        1       42.9538   1.7000      52.3 1.74810                                    2       18.6729   9.0000                                                      3       -1257.1068                                                                              1.2000      52.3 1.74810                                    4       67.2504   0.5000                                                      5       27.7414   3.6000      28.6 1.79504                                    6       51.3930   (d6)                                                        7       34.7935   4.0000      58.5 1.65160                                    8       -22.9172  1.0000      38.0 1.60342                                    9       313.8602  1.0000                                                      10      17.8387   1.0000      31.6 1.75692                                    11      15.3780   (d11)                                                       12      (diaphragm)                                                                             0.0000                                                      13      18.7094   4.0000      35.2 1.74950                                    14      45.8231   1.5000                                                      15      -368.2824 6.0000      28.3 1.72825                                    16      17.8973   2.0000                                                      17      39.4924   4.5000      48.0 1.71700                                    18      -68.5074                                                              ______________________________________                                        Table of variable distances:                                                  ______________________________________                                        f       36.00         50.00    68.00                                          R       inf           inf      inf                                            d6      28.09724      12.76604 2.28664                                        d11     9.80868       14.10148 10.32888                                       f       36.00         50.00    68.00                                          R       500.00        500.00   500.00                                         d6      34.22707      18.59607 8.24860                                        d11     3.67885       8.27145  4.36692                                        ______________________________________                                    

Values corresponding to the conditions:

β2t=6.680

β2w=-4.566

f2/f3=1.000

f2/(|f1|+e1t)=1.176

f2/(|f1|+e1w)=0.820

f3/e3w=1.187

f3/e3t=0.831

FIGS. 32A to 32C and 33A to 33C are aberration charts of the embodiment9 at a phototaking distance R=inf., respectively at the wide angle endand at the telephoto end, while FIGS. 34A to 34C and 35A to 35C areaberration charts of the embodiment 9 at a phototaking distance R=500,respectively at the wide angle end and at the telephoto end. In thesecharts, FNO indicates F-number, NA indicates numerical aperture, Yindicates image height, d indicates d-line (λ=587.6 nm) and g indicatesg-line (λ=435.6 nm). In the astigmatism chart, the solid line and thebroken line respectively indicate the sagittal and meridional planes.

These aberration charts indicates that the present embodiment issatisfactorily corrected for the various aberrations, and has excellentimaging performance.

[Embodiment 10]

FIGS. 36A and 36B are views showing the configuration of the zoom lensof an embodiment 10, respectively at the wide angle end and at thetelephoto end. The zoom lens is composed, in the order from the objectside, of a negative first lens group G1, a positive second lens groupG2, a diaphragm, a positive third lens group G3, and a negative fourthlens group G4, wherein, at the zooming from the wide angle end to thetelephoto end, the first and fourth lens groups remain fixed while thesecond and third lens groups move toward the object side, the air gapbetween the first and second lens groups decreases while that betweenthe second and third lens groups increases in the vicinity of the wideangle end and decreases in the vicinity of the telephoto end, and thatbetween the third and fourth lens groups increases.

The second lens face, from the object side, in the first lens group isan aspherical face, the shape of which is given by:

    X(y)=y.sup.2 /[r·{1+(1-k·y.sup.2 /r.sup.2).sup.1/2 }]+C2·y.sup.2 +C4·y.sup.4 +C6·y.sup.6 +C8·y.sup.8 +C10·y.sup.10

wherein X(y) is the axial distance from a tangential plane at the vertexof the aspherical face to a point of a height y on the aspherical face,r is the radius of paraxial curvature, k is the conical constant, and Ciis the i-th order aspherical coefficient.

The focusing from a long object distance to a short object distance isachieved by a movement of the second lens group toward the image plane.

The following Table 10 shows the parameters of the embodiment 10 of thepresent invention, wherein f is the focal length, F is the F-number and2ω is the image angle. The numbers in the left-hand column indicate theorder from the object side, r indicates the radius of curvature of thelens face, d is the distance between the lens faces, n and ν are therefractive index and the Abbe's number for d-line (λ=587.6 nm). R in thetable of variable distances indicates the phototaking distance.

                  TABLE 10                                                        ______________________________________                                        f = 25.85-35.00-48.80                                                         F/3.59-4.06-4.82                                                              2ω = 82.36-63.05-47.17°                                          r             d           ν   n                                            ______________________________________                                        1       33.9136   2.2500      60.0 1.64000                                    2       14.8847   8.0000                                                      3       57.9384   1.4400      55.6 1.69680                                    4       21.4272   4.1400                                                      5       22.6601   3.6000      25.5 1.73038                                    6       39.3975   (d6)                                                        7       141.9564  2.2000      67.9 1.59319                                    8       -30.3117  0.3700                                                      9       -34.1460  0.9000      26.1 1.78470                                    10      -51.9266  (d10)                                                       11      (diaphragm)                                                                             0.2000                                                      12      19.2304   2.6394      42.0 1.66755                                    13      69.8977   1.9603                                                      14      -42.4063  5.5739      31.6 1.75692                                    15      25.3216   1.1000                                                      16      138.5052  3.1182      59.6 1.53996                                    17      -22.6525  2.8000                                                      18      -83.5118  2.3534      70.0 1.51860                                    19      -30.5445  (d19)                                                       20      -21.7666  1.7864      64.1 1.51680                                    21      -25.1077                                                              ______________________________________                                    

Aspherical coefficients of second face:

k=0.7249

C2=0.0000

C4=0.0000

C6=0.0000

C8=3.6018E-11

C10=-1.8653E-13

    ______________________________________                                        Table of variable distances:                                                  ______________________________________                                        f       25.85         35.00    48.80                                          R       inf           inf      inf                                            d6      26.10426      12.71992 1.58658                                        d10     3.47119       9.09754  8.05943                                        d19     6.72166       14.47964 26.65110                                       f       25.85         35.00    48.80                                          R       500.00        500.00   500.00                                         d6      29.15901      15.65564 4.63303                                        d10     0.41644       6.16182  5.01298                                        d19     6.72166       14.47964 26.65110                                       ______________________________________                                    

Values corresponding to the conditions:

β2t=5.205

β2w=-5.075

f2/f3=1.157

f2/(|f1|+e1t)=1.238

f2/(|f1|+e1w)=0.835

f3/e3w=1.022

f3/e3t=0.744

FIGS. 37A to 37C and 38A to 38C are aberration charts of the embodiment10 at a phototaking distance R=inf., respectively at the wide angle endand at the telephoto end, while FIGS. 39A to 39C and 40A to 40C areaberration charts of the embodiment 10 at a phototaking distance R=500,respectively at the wide angle end and at the telephoto end. In thesecharts, FNO indicates F-number, NA indicates numerical aperture, Yindicates image height, d indicates d-line (λ=587.6 nm) and g indicatesg-line (λ=435.6 nm). In the astigmatism chart, the solid line and thebroken line respectively indicate the sagittal and meridional planes.

These aberration charts indicate that the present embodiment issatisfactorily corrected for the various aberrations, and has excellentimaging performance.

[Embodiment 11]

FIGS. 41A and 41B are views showing the configuration of the zoom lensof an embodiment 11, respectively at the wide angle end and at thetelephoto end. The zoom lens is composed, in the order from the objectside, of a negative first lens group G1, a positive second lens groupG2, a diaphragm, a positive third lens group G3 and a negative fourthlens group, wherein, at the zooming from the wide angle end to thetelephoto end, the first and fourth lens groups remain fixed while thesecond and third lens groups move toward the object side, the air gapbetween the first and second lens groups decreases while that betweenthe second and third lens groups increases in the vicinity of the wideangle end and decreases in the vicinity of the telephoto end, and thatbetween the third and fourth lens groups increases.

The focusing from a long object distance to a short object distance isachieved by a movement of the second lens group toward the image plane.

The following Table 11 shows the parameters of the embodiment 11 of thepresent invention, wherein f is the focal length, F is the F-number and2ω is the image angle. The numbers in the left-hand column indicate theorder from the object side, r indicates the radius of curvature of thelens face, d is the distance between the lens faces, n and ν are therefractive index and the Abbe's number for d-line (λ=587.6 nm). R in thetable of variable distances indicates the phototaking distance.

                  TABLE 11                                                        ______________________________________                                        f = 41.00-55.00-78.00                                                         F/4.10-4.82-6.01                                                              2ω = 58.08-43.29-30.77°                                          r             d           ν   n                                            ______________________________________                                        1       56.1797   1.7000      58.5 1.65160                                    2       19.0753   9.0000                                                      3       -102.6072 1.2000      55.6 1.69680                                    4       -402.8601 0.5000                                                      5       23.8515   3.6000      30.0 1.69895                                    6       30.4342   (d6)                                                        7       26.5142   4.0000      57.0 1.62280                                    8       -45.0000  1.0000      38.8 1.67163                                    9       3813.9157 1.0000                                                      10      18.6686   1.0000      35.7 1.90265                                    11      15.1761   (d11)                                                       12      (diaphragm)                                                                             0.0000                                                      13      15.9858   4.0000      49.7 1.55200                                    14      138.2929  1.5000                                                      15      -153.5728 6.0000      35.2 1.74950                                    16      15.3828   2.0000                                                      17      27.3218   4.5000      47.2 1.67003                                    18      -89.4819  (d18)                                                       19      355.8035  1.2526      60.0 1.64000                                    20      124.5345                                                              ______________________________________                                        Table of variable distances:                                                  ______________________________________                                        f       41.00         55.00    78.00                                          R       inf           inf      inf                                            d6      29.85350      16.02182 3.99996                                        d11     10.00955      14.11697 10.05648                                       d18     6.99989       16.72415 32.80650                                       f       41.00         55.00    78.00                                          R       500.00        500.00   500.00                                         d6      36.05087      21.92996 10.04931                                       d11     3.81218       8.20883  4.00713                                        d18     6.99989       16.72415 32.80650                                       ______________________________________                                    

Values corresponding to the conditions:

β2t=6.463

β2w=-4.660

f2/f3=1.000

f2/(|f1|+e1t)=1.183

f2/(|f1|+e1w)=0.823

f3/e3w=1.090

f3/e3t=0.777

FIGS. 42A to 42C and 43A to 43C are aberration charts of the embodiment11 at a phototaking distance R=inf., respectively at the wide angle endand at the telephoto end, while FIGS. 44A to 44C and 45A to 45C areaberration charts of the embodiment 11 at a phototaking distance R=500,respectively at the wide angle end and at the telephoto end. In thesecharts, FNO indicates F-number, NA indicates numerical aperture, Yindicates image height, d indicates d-line (λ=587.6 nm) and g indicatesg-line (λ=435.6 nm). In the astigmatism chart, the solid line and thebroken line respectively indicate the sagittal and meridional planes.

These aberration charts indicate that the present embodiment issatisfactorily corrected for the various aberrations, and has excellentimaging performance.

[Embodiment 12]

FIGS. 46A and 46B are views showing the configuration of the zoom lensof an embodiment 12, respectively at the wide angle end and at thetelephoto end. The zoom lens is composed, in the order from the objectside, of a negative first lens group G1, a positive second lens groupG2, a positive third lens group G3 and a negative fourth lens group,wherein, at the zooming from the wide angle end to the telephoto end,the first and fourth lens groups remain fixed while the second and thirdlens groups move toward the object side, the air gap between the firstand second lens groups decreases while that between the second and thirdlens groups increases in the vicinity of the wide angle end anddecreases in the vicinity of the telephoto end, and that between thethird and fourth lens groups increases.

The lens face closest to the object side in the fourth lens group is anaspherical face, the shape of which is given by:

    X(y)=y.sup.2 /[r·{1+(1-k·y.sup.2 /r.sup.2).sup.1/2 }]+C2·y.sup.2 +C4·y.sup.4 +C6·y.sup.6 +C8·y.sup.8 +C10·y.sup.10

wherein X(y) is the axial distance from a tangential plane at the vertexof the aspherical face to a point of a height y on the aspherical face,r is the radius of paraxial curvature, k is the conical constant, and Ciis the i-th order aspherical coefficient.

The focusing from a long object distance to a short object distance isachieved by a movement of the second lens group toward the image plane.

The following Table 12 shows the parameters of the embodiment 12 of thepresent invention, wherein f is the focal length, F is the F-number and2ω is the image angle. The numbers in the left-hand column indicate theorder from the object side, r indicates the radius of curvature of thelens face, d is the distance between the lens faces, n and ν are therefractive index and the Abbe's number for d-line (λ=587.6 nm). R in thetable of variable distances indicates the phototaking distance.

                  TABLE 12                                                        ______________________________________                                        f = 36.00-50.00-68.00                                                         F/3.61-4.08-4.61                                                              2ω = 64.10-48.07-36.98°                                          r             d           ν   n                                            ______________________________________                                        1       46.4394   1.9813      42.7 1.57309                                    2       21.3054   10.4895                                                     3       -321.3854 1.3986      50.2 1.72000                                    4       48.7004   0.5827                                                      5       31.3413   4.1958      28.6 1.79504                                    6       71.2763   (d6)                                                        7       41.3074   4.6620      57.0 1.62280                                    8       -60.0000  1.1655      38.8 1.67163                                    9       -329.9649 1.1655                                                      10      25.0017   1.1655      39.6 1.80454                                    11      21.3604   (d11)                                                       12      (diaphragm)                                                                             0.5000                                                      13      18.1079   4.6620      60.0 1.64000                                    14      62.6501   1.7483                                                      15      -88.4360  7.0000      35.2 1.74950                                    16      19.5170   2.3310                                                      17      65.4577   4.0000      49.5 1.77279                                    18      -46.2966  (d18)                                                       19      174.5061  3.0000      60.0 1.64000                                    20      -1067.7624                                                            ______________________________________                                    

Aspherical coefficients of nineteenth face:

k=1.0000

C2=0.0000

C4=3.1795E-6

C6=2.0784E-9

C8=-3.4864E-12

C10=0.0000

    ______________________________________                                        Table of variable distances:                                                  ______________________________________                                        f       36.00         50.00    68.00                                          R       inf           inf      inf                                            d6      33.08385      15.55442 3.82044                                        d11     12.42458      16.23870 10.62519                                       d18     3.92552       17.64084 34.98832                                       f       36.00         50.00    68.00                                          R       600.00        600.00   600.00                                         d6      39.85425      22.04028 10.46333                                       d11     5.65418       9.75284  3.98230                                        d18     3.92552       17.64084 34.98832                                       ______________________________________                                    

Values corresponding to the conditions:

β2t=6.446

β2w=-4.912

f2/f3=0.979

f2/(|f1|+e1t)=1.184

f2/(|f1|+e1w)=0.831

f3/e3w=1.325

f3/e3t=0.887

FIGS. 47A to 47C and 48A to 48C are aberration charts of the embodiment12 at a phototaking distance R=inf., respectively at the wide angle endand at the telephoto end, while FIGS. 49A to 49C and 50A to 50C areaberration charts of the embodiment 12 at a phototaking distance R=500,respectively at the wide angle end and at the telephoto end. In thesecharts, FNO indicates F-number, NA indicates numerical aperture, Yindicates image height, d indicates d-line (λ=587.6 nm) and g indicatesg-line (λ=435.6 nm). In the astigmatism chart, the solid line and thebroken line respectively indicate the sagittal and meridional planes.

These aberration charts indicate that the present embodiment issatisfactorily corrected for the various aberrations, and has excellentimaging performance.

[Embodiment 13]

FIGS. 51A and 51B are views showing the configuration of the zoom lensof an embodiment 13, respectively at the wide angle end and at thetelephoto end. The zoom lens is composed, in the order from the objectside, of a negative first lens group G1, a positive second lens groupG2, a diaphragm and a positive third lens group G3, wherein, at thezooming from the wide angle end to the telephoto end, the first lensgroup moves to the image side at the wide angle side and to the objectside at the telephoto side while the second and third lens groups movetoward the object side, the air gap between the first and second lensgroups decreases and that between the second and third lens groupsincreases.

The focusing from a long object distance to a short object distance isachieved by a movement of the second lens group toward the image plane.

The following Table 13 shows the parameters of the embodiment 13 of thepresent invention, wherein f is the focal length, F is the F-number and2ω is the image angle. The numbers in the left-hand column indicate theorder from the object side, r indicates the radius of curvature of thelens face, d is the distance between the lens faces, n and ν are therefractive index and the Abbe's number for d-line (λ=587.6 nm). R in thetable of variable distances indicates the phototaking distance.

                  TABLE 13                                                        ______________________________________                                        f = 36.00 - 50.00 - 68.00                                                     F/3.49 - 4.35 - 5.58                                                          2ω= 64.94 - 47.27 - 35.21°                                       r             d           ν   n                                            ______________________________________                                        1       36.4521   1.5000      55.6 1.69680                                    2       15.8918   8.3000                                                      3       -44.0087  1.1000      49.5 1.74443                                    4       81.9753   0.5000                                                      5       34.0100   4.6000      35.7 1.62588                                    6       -79.4645  (d 6)                                                       7       21.0405   4.0000      61.1 1.58913                                    8       -80.0000  1.0000      30.0 1.69895                                    9       278.0934  1.0000                                                      10      17.5841   1.0000      35.2 1.74950                                    11      13.4967   (d11)                                                       12      (diaphragm)                                                                             0.5000                                                      13      19.7452   4.0000      38.8 1.67163                                    14      -111.4451 1.0000                                                      15      -49.8231  6.0000      29.5 1.71736                                    16      19.0209   1.0000                                                      17      52.0805   4.5000      40.3 1.60717                                    18      -59.7886                                                              ______________________________________                                        Table of variable distances:                                                  ______________________________________                                        f       36.00         50.00    68.00                                          R       inf           inf      inf                                            d6      24.21825      10.54825 1.00115                                        d11     9.62060       10.91310 12.61650                                       f       36.00         50.00    68.00                                          R       500.00        500.00   500.00                                         d6      29.34137      15.49170 6.16728                                        d11     4.49748       5.96965  7.45037                                        ______________________________________                                    

Values corresponding to the conditions:

|f1|/fw=1.278

f2/f3=0.957

x2/x3=1.129

f2/(|f1|+e1w)=0.846

f2/(|f1|+e1t)=1.196

β2t=6.102

β2w=-5.475

f3/e3w=1.137

f3/e3t=0.826

FIGS. 52A to 52C and 53A to 53C are aberration charts of the embodiment13 at a phototaking distance R=inf., respectively at the wide angle endand at the telephoto end, while FIGS. 54A to 54C and 55A to 55C areaberration charts of the embodiment 13 at a phototaking distance R=500,respectively at the wide angle end and at the telephoto end. In thesecharts, FNO indicates F-number, NA indicates numerical aperture, Yindicates image height, d indicates d-line (λ=587.6 nm) and g indicatesg-line (λ=435.6 nm). In the astigmatism chart, the solid line and thebroken line respectively indicate the sagittal and meridional planes.

These aberration charts indicate that the present embodiment issatisfactorily corrected for the various aberrations, and has excellentimaging performance.

[Embodiment 14]

FIGS. 56A and 56B are views showing the configuration of the zoom lensof an embodiment 14, respectively at the wide angle end and at thetelephoto end. The zoom lens is composed, in the order from the objectside, of a negative first lens group G1, a positive second lens groupG2, a diaphragm, a positive third lens group G3 and a negative fourthlens group G4, wherein, at the zooming from the wide angle end to thetelephoto end, the first lens group moves toward the image side at thewide angle side and toward the object side at the telephoto side, whilethe second and third lens groups move toward the object side, the fourthlens group remains fixed, the air gap between the first and second lensgroups decreases while that between the second and third lens groupsincreases and that between the third and fourth lens groups increases.

The focusing from a long object distance to a short object distance isachieved by a movement of the second lens group toward the image plane.

The following Table 14 shows the parameters of the embodiment 14 of thepresent invention, wherein f is the focal length, F is the F-number and2ω is the image angle. The numbers in the left-hand column indicate theorder from the object side, r indicates the radius of curvature of thelens face, d is the distance between the lens faces, n and ν are therefractive index and the Abbe's number for d-line (λ=587.6 nm). R in thetable of variable distances indicates the phototaking distance.

                  TABLE 14                                                        ______________________________________                                        f = 41.00 - 55.00 - 78.00                                                     F/4.03 - 4.81 - 5.97                                                          2ω = 57.58 - 42.24 - 30.59°                                      r             d           ν   n                                            ______________________________________                                        1       71.4000   1.6000      58.5 1.65160                                    2       18.7000   8.3000                                                      3       -93.3000  1.1000      55.6 1.69680                                    4       206.8600  0.5000                                                      5       31.1000   3.3000      31.1 1.68893                                    6       80.8811   (d6)                                                        7       27.2400   3.8000      57.0 1.62280                                    8       -41.0000  1.0000      37.9 1.72342                                    9       -176.1500 1.0000                                                      10      21.3000   1.0000      27.6 1.75520                                    11      15.8899   (d11)                                                       12      (diaphragm)                                                                             0.5000                                                      13      15.3600   4.0000      45.9 1.54814                                    14      115.2212  1.0000                                                      15      -118.5000 6.0000      35.2 1.74950                                    16      15.6240   1.5000                                                      17      29.5000   4.5000      47.1 1.67003                                    18      -66.4454  (d18)                                                       19      78.2000   1.5000      60.0 1.64000                                    20      55.1518                                                               ______________________________________                                        Table of variable distances:                                                  ______________________________________                                        f       41.00         55.00    78.00                                          R       inf           inf      inf                                            d6      25.41124      12.32584 1.97394                                        d11     8.50475       9.71815  11.54295                                       d18     1.02639       11.94699 28.37009                                       f       41.00         55.00    78.00                                          R       500.00        500.00   500.00                                         d6      30.59858      17.32515 7.21035                                        d11     3.31741       4.71884  6.30654                                        d18     1.02639       11.94699 28.37009                                       ______________________________________                                    

Values corresponding to the conditions:

|f1|/fw=1.122

f2/f3=0.957

x2/x3=1.111

f2/(|f1|+e1w)=0.845

f2/(|f1|+e1t)=1.199

β2t=6.017

β2w=-5.446

FIGS. 57A to 57C and 58A to 58C are aberration charts of the embodiment14 at a phototaking distance R=inf., respectively at the wide angle endand at the telephoto end, while FIGS. 59A to 59C and 60A to 60C areaberration charts of the embodiment 14 at a phototaking distance R=500,respectively at the wide angle end and at the telephoto end. In thesecharts, FNO indicates F-number, NA indicates numerical aperture, Yindicates image height, d indicates d-line (λ=587.6 nm) and g indicatesg-line (λ=435.6 nm). In the astigmatism chart, the solid line and thebroken line respectively indicate the sagittal and meridional planes.

These aberration charts indicate that the present embodiment issatisfactorily corrected for the various aberrations, and has excellentimaging performance.

[Embodiment 15]

FIGS. 61A and 61B are views showing the configuration of the zoom lensof an embodiment 15, respectively at the wide angle end and at thetelephoto end. The zoom lens is composed, in the order from the objectside, of a negative first lens group G1, a positive second lens groupG2, a diaphragm and a positive third lens group G3, wherein, at thezooming from the wide angle end to the telephoto end, the first lensgroup moves toward the image side at the wide angle side and toward theobject side at the telephoto side, while the second and third lensgroups move toward the object side, the air gap between the first andsecond lens groups decreases and that between the second and third lensgroups increases in the vicinity of the wide angle end and decreases inthe vicinity of the telephoto end.

The focusing from a long object distance to a short object distance isachieved by a movement of the second lens group toward the image plane.

The following Table 15 shows the parameters of the embodiment 15 of thepresent invention, wherein f is the focal length, F is the F-number and2ω is the image angle. The numbers in the left-hand column indicate theorder from the object side, r indicates the radius of curvature of thelens face, d is the distance between the lens faces, n and ν are therefractive index and the Abbe's number for d-line (λ=587.6 nm). R in thetable of variable distances indicates the phototaking distance.

                  TABLE 15                                                        ______________________________________                                        f = 29.02 - 35.00 - 53.93                                                     F/3.97 - 4.88 - 5.76                                                          2ω = 76.32 - 56.01 - 42.91°                                      r             d           ν   n                                            ______________________________________                                        1       37.2114   1.5000      57.5 1.67025                                    2       17.5647   9.0000                                                      3       219.3762  1.5000      46.8 1.76684                                    4       23.9348   1.5000                                                      5       23.2030   3.9000      35.2 1.74950                                    6       85.5901   (d6)                                                        7       35.6990   3.8000      60.0 1.64000                                    8       -57.4167  1.0000      25.5 1.80518                                    9       -86.7285  1.0000                                                      10      27.4452   1.5000      28.6 1.79504                                    11      19.8264   2.0000                                                      12      (diaphragm)                                                                             (d12)                                                       13      17.9894   3.5000      35.2 1.74950                                    14      -51.6005  1.0000                                                      15      -28.8329  4.8000      28.6 1.79504                                    16      18.9279   1.3000                                                      17      -69.9586  3.6000      56.1 1.56883                                    18      -17.4637                                                              ______________________________________                                        Table of variable distances:                                                  ______________________________________                                        f       29.02         35.00    53.93                                          R       inf           inf      inf                                            d6      23.69493      9.80393  0.99703                                        d12     6.76153       6.89333  5.20253                                        f       29.02         35.00    53.93                                          R       500.00        500.00   500.00                                         d6      27.83455      13.84173 5.19807                                        d12     2.62191       2.85553  1.00149                                        ______________________________________                                    

Values corresponding to the conditions:

|f1|/fw=1.447

f2/f3=1.182

x2/x3=0.922

f2/(|f1|+e1w)=0.877

f2/(|f1|+e1t)=1.265

β2t=4.777

β2w=-7.149

f3/e3w=1.107

f3/e3t=0.788

FIGS. 62A to 62C and 63A to 63C are aberration charts of the embodiment15 at a phototaking distance R=inf., respectively at the wide angle endand at the telephoto end, while FIGS. 64A to 64C and 65A to 65C areaberration charts of the embodiment 15 at a phototaking distance R=500,respectively at the wide angle end and at the telephoto end. In thesecharts, FNO indicates F-number, NA indicates numerical aperture, Yindicates image height, d indicates d-line (λ=587.6 nm) and g indicatesg-line (λ=435.6 nm). In the astigmatism chart, the solid line and thebroken line respectively indicate the sagittal and meridional planes.

These aberration charts indicate that the present embodiment issatisfactorily corrected for the various aberrations, and has excellentimaging performance.

[Embodiment 16]

FIGS. 66A and 66B are views showing the configuration of the zoom lensof an embodiment 16, respectively at the wide angle end and at thetelephoto end. The zoom lens is composed, in the order from the objectside, of a negative first lens group G1, a positive second lens groupG2, a diaphragm and a positive third lens group G3, wherein, at thezooming from the wide angle end to the telephoto end, the first lensgroups moves toward the image side at the wide angle side and toward theobject side at the telephoto side, while the second and third lensgroups move toward the object side, the air gap between the first andsecond lens groups decreases and that between the second and third lensgroups decreases.

The second lens face, from the object side, in the first lens group isan aspherical face, the shape of which is given by:

    X(y)=y.sup.2 /[r·{1+(1-k·y.sup.2 /r.sup.2).sup.1/2 }]+C2·y.sup.2 +C4·y.sup.4 +C6·y.sup.6 +C8·y.sup.8 +C10·y.sup.10

wherein X(y) is the axial distance from a tangential plane at the vertexof the aspherical face to a point of a height y on the aspherical face,r is the radius of paraxial curvature, k is the conical constant, and Ciis the i-th order aspherical coefficient.

The following Table 16 shows the parameters of the embodiment 16 of thepresent invention, wherein f is the focal length, F is the F-number and2ω is the image angle. The numbers in the left-hand column indicate theorder from the object side, r indicates the radius of curvature of thelens face, d is the distance between the lens faces, n and ν are therefractive index and the Abbe's number for d-line (λ=587.6 nm). R in thetable of variable distances indicates the phototaking distance.

                  TABLE 16                                                        ______________________________________                                        f = 25.61 - 35.00 - 48.80                                                     F/4.06 - 4.69 - 5.60                                                          2ω =82.82 - 63.85 - 47.73°                                       r             d           ν   n                                            ______________________________________                                        1       68.0036   2.6507      53.8 1.69350                                    2       15.3447   5.8500                                                      3       36.9646   2.3412      47.5 1.78797                                    4       24.6442   4.4493                                                      5       23.7865   4.0233      25.5 1.73038                                    6       42.9447   (d6)                                                        7       146.1275  2.1985      82.5 1.49782                                    8       -41.3538  (d8)                                                        9       (diaphragm)                                                                             0.1000                                                      10      22.8142   5.0000      46.4 1.58267                                    11      -43.2776  0.9000                                                      12      -25.4294  8.0000      31.6 1.75692                                    13      28.8306   1.7500                                                      14      -50.2391  2.7159      67.9 1.59319                                    15      -17.9559  1.1000                                                      16      -65.7206  2.0333      82.5 1.49782                                    17      -30.7708                                                              ______________________________________                                    

Aspherical coefficients of second face:

k=0.5871

C2=0.0000

C4=-7.3809E-10

C6=3.5998E-14

C8=-4.7697E-12

C10=1.8500E-14

    ______________________________________                                        Table of variable distances:                                                  ______________________________________                                        f       25.50         35.00    48.80                                          R       inf           inf      inf                                            d6      25.03527      11.75045 1.61160                                        d8      4.90539       4.45554  3.80098                                        f       25.50         35.00    48.80                                          R       500.00        500.00   500.00                                         d6      28.14368      14.73325 4.71730                                        d8      1.79698       1.47275  0.69528                                        ______________________________________                                    

Values corresponding to the conditions:

|f1|/fw=1.386

f2/f3=1.066

x2/x3=0.952

f2/(|f1|+e1w)=0.850

f2/(|f1|+e1t)=1.226

β2t=5.433

β2w=-5.672

f3/e3w=1.146

f3/e3t=0.798

FIGS. 67A to 67C and 68A to 68C are aberration charts of the embodiment16 at a phototaking distance R=inf., respectively at the wide angle endand at the telephoto end, while FIGS. 69A to 69C and 70A to 70C areaberration charts of the embodiment 16 at a phototaking distance R=500,respectively at the wide angle end and at the telephoto end. In thesecharts, FNO indicates F-number, NA indicates numerical aperture, Yindicates image height, d indicates d-line (λ=587.6 nm) and g indicatesg-line (λ=435.6 nm). In the astigmatism chart, the solid line and thebroken line respectively indicate the sagittal and meridional planes.

These aberration charts indicate that the present embodiment issatisfactorily corrected for the various aberrations, and has excellentimaging performance.

[Embodiment 17]

FIGS. 71A and 71B are views showing the configuration of the zoom lensof an embodiment 17, respectively at the wide angle end and at thetelephoto end. The zoom lens is composed, in the order from the objectside, of a negative first lens group G1, a positive second lens groupG2, a diaphragm and a positive third lens group G3, wherein, at thezooming from the wide angle end to the telephoto end, the first lensgroup remains fixed while the second and third lens groups move towardthe object side, the air gap between the first and second lens groupsdecreases and that between the second and third lens groups increases inthe vicinity of the wide angle end and decreases in the vicinity of thetelephoto end.

The focusing from a long object distance to a short object distance isachieved by a movement of the second lens group toward the image plane.

The following Table 17 shows the parameters of the embodiment 17 of thepresent invention, wherein f is the focal length, F is the F-number and2ω is the image angle. The numbers in the left-hand column indicate theorder from the object side, r indicates the radius of curvature of thelens face, d is the distance between the lens faces, n and ν are therefractive index and the Abbe's number for d-line (λ=587.6 nm). R in thetable of variable distances indicates the phototaking distance.

                  TABLE 17                                                        ______________________________________                                        f = 36.00 - 50.00 - 68.00                                                     F/3.62 - 4.50 - 5.63                                                          2ω = 65.13 - 47.14 - 35.15°                                      r             d           ν   n                                            ______________________________________                                        1       43.1721   1.7000      52.3 1.74810                                    2       18.7358   9.0000                                                      3       -1028.3813                                                                              1.2000      52.3 1.74810                                    4       58.6589   0.5000                                                      5       28.5391   3.6000      28.6 1.79504                                    6       61.5275   (d6)                                                        7       34.2399   4.0000      58.5 1.65160                                    8       -23.8972  1.0000      38.0 1.60342                                    9       300.7253  1.0000                                                      10      18.1228   1.0000      31.6 1.75692                                    11      15.5482   (d11)                                                       12      (diaphragm)                                                                             0.2000                                                      13      18.7977   4.0000      35.2 1.74950                                    14      45.2035   1.5000                                                      15      -292.0245 6.0000      28.3 1.72825                                    16      18.1901   2.0000                                                      17      40.3435   4.5000      48.0 1.71700                                    18      -63.6092                                                              ______________________________________                                        Table of variable distances:                                                  ______________________________________                                        f       36.00         50.00    68.00                                          R       inf           inf      inf                                            d6      27.81068      12.47948 2.00008                                        d11     9.12937       13.42177 9.64957                                        f       36.00         50.00    68.00                                          R       500.00        500.00   500.00                                         d6      33.94051      18.30951 7.96204                                        d11     2.99954       7.59174  3.68761                                        ______________________________________                                    

Values corresponding to the conditions:

|f1|/fw=1.389

f2/f3=1.000

x2/x3=1.021

f2/(|f1|+e1w)=0.820

f2/(|f1|+e1t)=1.176

β2t=6.680

β2w=-4.566

f3/e3w=1.187

f3/e3t=0.831

FIGS. 72A to 72C and 73A to 73C are aberration charts of the embodiment17 at a phototaking distance R=inf., respectively at the wide angle endand at the telephoto end, while FIGS. 74A to 74C and 75A to 75C areaberration charts of the embodiment 17 at a phototaking distance R=500,respectively at the wide angle end and at the telephoto end. In thesecharts, FNO indicates F-number, NA indicates numerical aperture, Yindicates image height, d indicates d-line (λ=587.6 nm) and g indicatesg-line (λ=435.6 nm). In the astigmatism chart, the solid line and thebroken line respectively indicate the sagittal and meridional planes.

These aberration charts indicate that the present embodiment issatisfactorily corrected for the various aberrations, and has excellentimaging performance.

[Embodiment 18]

The zoom lens of the embodiment 18 is the same, in the configuration andin the parameters, as that of the embodiment 11, except for thefollowing values of the conditions, and the aberration charts are alsothe same as those of the embodiment 11:

Values corresponding to the conditions:

|f1|/fw=1.220

f2/f3=1.000

x2/x3=1.002

f2/(|f1|+e1w)=0.823

f2/(|f1|+e1t)=1.183

β2t=6.463

β2w=-4.660

[Embodiment 19]

FIGS. 76A and 76B are views showing the configuration of the zoom lensof an embodiment 19, respectively at the wide angle end and at thetelephoto end. The zoom lens is composed, in the order from the objectside, of a negative first lens group G1, a positive second lens groupG2, a diaphragm and a positive third lens group G3, wherein, at thezooming from the wide angle end to the telephoto end, the first lensgroup remains fixed while the second and third lens groups move towardthe object side, the air gap between the first and second lens groupsdecreases and that between the second and third lens groups increases inthe vicinity of the wide angle end and decreases in the vicinity of thetelephoto end.

The fourth lens face, from the object side, in the first lens group isan aspherical face, the shape of which is given by:

    X(y)=y.sup.2 /[r·{1+(1-k·y.sup.2 /r.sup.2).sup.1/2 }]+C2·y.sup.2 +C4·y.sup.4 +C6·y.sup.6 +C8·y.sup.8 +C10·y.sup.10

wherein X(y) is the axial distance from a tangential plane at the vertexof the aspherical face to a point of a height y on the aspherical face,r is the radius of paraxial curvature, k is the conical constant, and Ciis the i-th order aspherical coefficient.

The focusing from a long object distance to a short object distance isachieved by a movement of the second lens group toward the image plane.

The following Table 19 shows the parameters of the embodiment 19 of thepresent invention, wherein f is the focal length, F is the F-number and2ω is the image angle. The numbers in the left-hand column indicate theorder from the object side, r indicates the radius of curvature of thelens face, d is the distance between the lens faces, n and ν are therefractive index and the Abbe's number for d-line (λ=587.6 nm). R in thetable of variable distances indicates the phototaking distance.

                  TABLE 19                                                        ______________________________________                                        f = 24.50 - 35.00 - 49.00                                                     F/3.97 - 4.63 - 5.62                                                          2ω = 84.70 - 63.27 - 47.72°                                      r             d           ν   n                                            ______________________________________                                        1       137.5419  2.7692      64.1 1.51680                                    2       777.1284  0.2769                                                      3       73.3356   2.3077      60.0 1.64000                                    4       14.8646   7.8000                                                      5       28.8487   2.0000      55.6 1.69680                                    6       21.1112   2.0000                                                      7       18.2571   4.0000      25.5 1.73038                                    8       24.0542   (d8)                                                        9       192.6173  2.1357      60.7 1.56384                                    10      -34.0596  0.9286      28.6 1.79504                                    11      -41.2855  (d11)                                                       12      (diaphragm)                                                                             0.3000                                                      13      18.8781   2.7290      42.0 1.66755                                    14      67.5287   1.1706                                                      15      -29.6285  5.5702      31.6 1.75692                                    16      29.1265   1.0909                                                      17      -182.8014 3.2751      67.9 1.59319                                    18      -27.2905  0.7839                                                      19      -104.5100 1.8182      64.1 1.51680                                    20      -19.9302                                                              ______________________________________                                    

Aspherical coefficients of fourth face:

k=0.7165

C2=0.0000

C4=-7.8400E-7

C6=1.2600E-9

C8=-4.7300E-12

C10=1.9400E-14

    ______________________________________                                        Table of variable distances:                                                  ______________________________________                                        f       24.50         35.00    49.00                                          R       inf           inf      inf                                            d8      27.37057      11.99727 1.93247                                        d11     3.43385       8.59145  5.24725                                        f       24.50         35.00    49.00                                          R       500.00        500.00   500.00                                         d8      30.51639      15.09256 5.19064                                        d11     0.28803       5.49616  1.98908                                        ______________________________________                                    

Values corresponding to the conditions:

|f1|/fw=1.469

f2/f3=1.182

x2/x3=1.077

f2/(|f1|+e1w)=0.868

f2/(|f1|+e1t)=1.315

β2t=4.170

β2w=-6.598

f3/e3w=1.115

f3/e3t=0.754

FIGS. 77A to 77C and 78A to 78C are aberration charts of the embodiment19 at a phototaking distance R=inf., respectively at the wide angle endand at the telephoto end, while FIGS. 79A to 79C and 80A to 80C areaberration charts of the embodiment 19 at a phototaking distance R=500,respectively at the wide angle end and at the telephoto end. In thesecharts, FNO indicates F-number, NA indicates numerical aperture, Yindicates image height, d indicates d-line (λ=587.6 nm) and g indicatesg-line (λ=435.6 nm). In the astigmatism chart, the solid line and thebroken line respectively indicate the sagittal and meridional planes.

These aberration charts indicate that the present embodiment issatisfactorily corrected for the various aberrations, and has excellentimaging performance.

[Embodiment 20]

The zoom lens of the embodiment 20 is the same, in the configuration andin the parameters, except for the following values corresponding to theconditions, as that of the embodiment 10, and the aberration charts arealso the same as those of the embodiment 10:

Values corresponding to the conditions:

|f1|/fw=1.358

f2/f3=1.157

x2/x3=1.101

f2/(|f1|+e1w)=0.835

f2/(|f1|+e1t)=1.238

β2t=5.205

β2w=-5.075

[Embodiment 21]

FIGS. 81A and 81B are views showing the configuration of the zoom lensof an embodiment 21, respectively at the wide angle end and at thetelephoto end. The zoom lens is composed, in the order from the objectside, of a negative first lens group G1, a positive second lens groupG2, a diaphragm, a positive third lens group G3 and a positive fourthlens group G4, wherein, at the zooming from the wide angle end to thetelephoto end, the first and fourth lens groups remain fixed while thesecond and third lens groups move toward the object side, the air gapbetween the first and second lens groups decreases while that betweenthe second and third lens groups increases in the vicinity of the wideangle end and decreases in the vicinity of the telephoto end, and thatbetween the third and fourth lens groups increases.

The second lens face, from the object side, in the first lens group isan aspherical face, the shape of which is given by:

    X(y)=y.sup.2 /[r·{1+(1-k·y.sup.2 /r.sup.2).sup.1/2 }]+C2·y.sup.2 +C4·y.sup.4 +C6·y.sup.6 +C8·y.sup.8 +C10·y.sup.10

wherein X(y) is the axial distance from a tangential plane at the vertexof the aspherical face to a point of a height y on the aspherical face,r is the radius of paraxial curvature, k is the conical constant, and Ciis the i-th order aspherical coefficient.

The focusing from a long object distance to a short object distance isachieved by a movement of the second lens group toward the image plane.

The following Table 21 shows the parameters of the embodiment 21 of thepresent invention, wherein f is the focal length, F is the F-number and2ω is the image angle. The numbers in the left-hand column indicate theorder from the object side, r indicates the radius of curvature of thelens face, d is the distance between the lens faces, n and ν are therefractive index and the Abbe's number for d-line (λ=587.6 nm). R in thetable of variable distances indicates the phototaking distance.

                  TABLE 21                                                        ______________________________________                                        f = 25.50 - 35.00 - 49.00                                                     F/3.47 - 4.11 - 4.73                                                          2ω = 82.56 - 62.90 - 47.60°                                      r             d           ν   n                                            ______________________________________                                        1       79.6622   3.0000      58.5 1.61272                                    2       14.9036   5.9348                                                      3       30.1296   2.3751      45.4 1.79668                                    4       22.5872   4.5000                                                      5       22.4103   4.0000      25.5 1.73038                                    6       33.2972   (d6)                                                        7       143.1473  1.6000      82.5 1.49782                                    8       -38.4004  (d8)                                                        9       (diaphragm)                                                                             0.5000                                                      10      21.8482   5.0000      47.0 1.56013                                    11      -55.8544  0.9429                                                      12      -28.8504  7.5429      31.1 1.68893                                    13      26.3305   1.8333                                                      14      -46.0254  2.8452      67.9 1.59319                                    15      -18.8797  1.5000                                                      16      -91.7202  2.1300      82.5 1.49782                                    17      -36.7451  (d17)                                                       18      161.9599  2.0000      64.1 1.51680                                    19      432.1271                                                              ______________________________________                                    

Aspherical coefficients of second face:

k=0.5590

C2=0.0000

C4=1.9300E-7

C6=3.1800E-9

C8=-3.0000E-12

C10=8.0000E-14

    ______________________________________                                        Table of variable distances:                                                  ______________________________________                                        f       25.85         35.00    48.80                                          R       inf           inf      inf                                            d6      23.11846      10.70690 1.65476                                        d8      7.95829       9.59439  3.51470                                        d17     0.46783       11.24329 26.37513                                       f       25.85         35.00    48.80                                          R       500.00        500.00   500.00                                         d6      26.13220      13.62221 4.65526                                        d8      4.94455       6.67908  0.51420                                        d17     0.46783       11.24329 26.37513                                       ______________________________________                                    

Values corresponding to the conditions:

|f1|/fw=1.373

f2/f3=0.953

x2/x3=0.828

f2/(|f1|+e1w)=0.852

f2/(|f1|+e1t)=1. 206

β2t=5.860

β2w=-5.746

FIGS. 82A to 82C and 83A to 83C are aberration charts of the embodiment21 at a phototaking distance R=inf., respectively at the wide angle endand at the telephoto end, while FIGS. 84A to 84C and 85A to 85C areaberration charts of the embodiment 21 at a phototaking distance R=500,respectively at the wide angle end and at the telephoto end. In thesecharts, FNO indicates F-number, NA indicates numerical aperture, Yindicates image height, d indicates d-line (λ=587.6 nm) and g indicatesg-line (λ=435.6 nm). In the astigmatism chart, the solid line and thebroken line respectively indicate the sagittal and meridional planes.

These aberration charts indicate that the present embodiment issatisfactorily corrected for the various aberrations, and has excellentimaging performance.

According to second and third aspects of the present invention, asexplained in the foregoing, there can be realized a zoom lens capable,even in the use of the inner focusing method, of maintaining the amountof focusing movement of the focusing lens group substantially constantfor a given object distance regardless of the zoom position, whereby thehigh-speed lens drive in the auto focusing and the convenience ofmanipulation in the manual focusing can both be achieved. Also, the useof the inner focusing method allows for fixing the lens group closest tothe object side, so that the zoom lens of the present invention issuitable for use in a waterdrop-proof, water-proof or dust-proof camera.

Furthermore, correcting of vibration is possible by moving one of thelens groups in a direction perpendicular to the optical axis. Therelatively small second or third lens group is preferably selected forthe correction of vibration in order to make more compact the drivingmechanism therefor.

What is claimed is:
 1. A zoom lens comprising at least, in order fromthe object side, a first lens group of a negative refractive power thatis closer to the object side than any other lens group of the zoom lens,a second lens group of a positive refractive power, a third lens groupof a positive refractive power, a fourth lens group of a negativerefractive power, and a fifth lens group of a positive refractive power,wherein, in the zooming operation from the wide angle end to thetelephoto end, the distance between the first and second lens groupsdecreases, the distance between the second and third lens groups varies,the distance between the third and fourth lens groups increases, thedistance between the fourth and fifth lens groups decreases, and thefollowing condition is satisfied:

    0.3<f2/f3<3

wherein f2: focal length of the second lens group; and f3: focal lengthof the third lens group.
 2. A zoom lens according to claim 1, whereinthe focusing operation from a long object distance to a short objectdistance is executed by a movement of said second lens group toward theimage plane.
 3. A zoom lens according to claim 1, wherein, in thezooming operation from the wide angle end to the telephoto end, thefirst lens group remains fixed.
 4. A zoom lens according to claim 3,wherein, in the zooming operation from the wide angle end to thetelephoto end, the fourth lens group remains fixed.
 5. A zoom lensaccording to claim 3, wherein, in the zooming operation from the wideangle end to the telephoto end, the third and fifth lens groups moveintegrally toward the object side.
 6. A zoom lens according to claim 1,wherein, in the zooming operation from the wide angle end to thetelephoto end, the first and fourth lens groups remain fixed, and thethird and fifth lens groups move integrally toward the object side.
 7. Azoom lens comprising at least, in order from the object side, a firstlens group of a negative refractive power that is closer to the objectside than any other lens group of the zoom lens, a second lens group ofa positive refractive power, a third lens group of a positive refractivepower, a fourth lens group of a negative refractive power, and a fifthlens group of a positive refractive power, wherein, in the zoomingoperation from the wide angle end to the telephoto end, the distancebetween the first and second lens groups decreases, the distance betweenthe second and third lens groups increases, the distance between thethird and fourth lens groups increases, and the distance between thefourth and fifth lens groups decreases.
 8. A zoom lens according toclaim 7, wherein the focusing operation from a long object distance to ashort object distance is executed by a movement of said second lensgroup toward the image plane.
 9. A zoom lens comprising, in order fromthe object side, a first lens group of a negative refractive power thatis closer to the object side than any other lens group of the zoom lens,a second lens group of a positive refractive power, a third lens groupof a positive refractive power, a fourth lens group of a negativerefractive power, and a fifth lens group of a positive refractive power,wherein, in the zooming operation from the wide angle end to thetelephoto end, the distance between said first and second lens groupsdecreases, the distance between said second and third lens groupsvaries, the distance between said third and fourth lens groupsincreases, and the distance between said fourth and fifth lens groupsdecreases.
 10. A zoom lens according to claim 9, wherein the focusingoperation from a long object distance to a short object distance isexecuted by a movement of said second lens group toward the image plane.11. A zoom lens according to claim 9, wherein, in the zooming operation,said first lens group remains fixed.